Showing papers on "Affinity chromatography published in 2010"

Cell separation using cryogel-based affinity chromatography

Abstract: In cell affinity chromatography, type-specific cell separation is based on the interaction between cell-surface receptors and an immobilized ligand on a stationary matrix. This protocol describes the preparation of monolithic polyacrylamide and polydimethylacrylamide cryogel affinity matrices that can be used as a generic type-specific cell separation approach. The supermacroporous monolithic cryogel has highly interconnected large pores (up to 100 μm) for convective migration of large particles such as mammalian cells. In this protocol, they are functionalized to immobilize a protein A ligand by a two-step derivatization of epoxy-containing cryogel monolith (reaction with ethylenediamine and glutaraldehyde). Target cells were labeled with specific antibodies and then they were captured in the cryogel through affinity with protein A. These specifically captured cells were recovered in high yields while retaining their viability by mechanical squeezing of the spongy and elastic cryogel matrices. The suggested cell separation protocol takes <30 min for complete separation on a preprepared protein A–immobilized cryogel column.

Purification and characterization of a new recombinant factor VIII (N8).

Abstract: SUMMARY A new recombinant factor VIII (FVIII), N8, has been produced in Chinese hamster ovary (CHO) cells. The molecule consists of a heavy chain of 88 kDa including a 21 amino acid residue truncated B-domain and a light chain of 79 kDa. The two chains are held together by non-covalent interactions. The four-step purification includes capture, affinity purification using a monoclonal recombinant antibody, anion exchange chromatography and gel filtration. The specific clotting activity of N8 was 8800-9800 IU mg(-1). Sequence and mass spectrometry analysis revealed two variants of the light chain, corresponding to two alternative N-terminal sequences also known from plasma FVIII. Two variants of the heavy chain are present in the purified product, namely with and without the B-domain linker attached. This linker is removed upon thrombin activation of N8 rendering an activated FVIII (FVIIIa) molecule similar to plasma FVIIIa. All six known tyrosine sulphations of FVIII were confirmed in N8. Two N-linked glycosylations are present in the A3 and C1 domain of the light chain and two in the A1 domain of the heavy chain. The majority of the N-linked glycans are sialylated bi-antennary structures. An O-glycosylation site is present in the B-domain linker region. This site was glycosylated with a doubly sialylated GalNAc-Gal structure in approximately 65% of the product. In conclusion, the present data show that N8 is a pure and well-characterized FVIII product with biochemical properties that equal other FVIII products.

Pharmacokinetics and brain uptake of a genetically engineered bifunctional fusion antibody targeting the mouse transferrin receptor.

Abstract: Monoclonal antibodies (MAbs) are potential new therapeutics for brain diseases. However, MAbs do not cross the blood−brain barrier (BBB). The present work describes the genetic engineering of a fusion protein composed of a therapeutic single chain Fv (ScFv) antibody and a mouse/rat chimeric MAb against the mouse transferrin receptor (TfR). The TfRMAb acts as a molecular Trojan horse to ferry the therapeutic ScFv across the BBB in vivo in the mouse. The ScFv is fused to the carboxyl terminus of the heavy chain of the chimeric TfRMAb, and this fusion protein is designated cTfRMAb-ScFv. Chinese hamster ovary cells were permanently transfected, and a high secreting cell line in serum free medium was cloned. The cTfRMAb-ScFv fusion protein was purified to homogeneity on gels and Western blotting with protein G affinity chromatography. The cTfRMAb-ScFv fusion protein was bifunctional and bound both the target antigen, as determined by ELISA, and the mouse TfR, as determined with a radio-receptor assay. The cTfR...

Profiling carbonylated proteins in human plasma.

Abstract: This study reports the first proteomic-based identification and characterization of oxidized proteins in human plasma. The study was conducted by isolating carbonylated proteins from the plasma of male subjects (age 32−36) with avidin affinity chromatography subsequent to biotinylation of carbonyl groups with biotin hydrazide and sodium cyanoborohydride reduction of the resulting Schiff’s bases. Avidin selected proteins were digested with trypsin, and the peptide fragments were separated by C18 reversed phase chromatography and identified and characterized by both electrospray ionization and matrix assisted laser desorption ionization mass spectrometry. Approximately 0.2% of the total protein in plasma was selected with this method. Sixty-five high, medium, and low abundance proteins were identified, the majority appearing in all subjects. An interesting feature of the oxidized proteins isolated was that in addition to carbonylation they often bore other types of oxidative modification. Twenty-four oxidat...

Isolation and Purification of Collagen al(1) Receptor from Human Platelet Membrane

Abstract: binding of these substances by platelet membranes. We now describe the isolation and purification of the receptor from isolated human platelet membrane. The receptor can be solubilized from platelet membranes with 0.5% Triton or 0.5% sodium deoxycholate. Using the combination of gel filtration, affinity column chromatography on al-Sepharose 4B, and preparative slab gel electrophoreses, the receptor protein can be purified to a single band as judged on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its activity was destroyed by incubation with trypsin or Pronase. The apparent molecular weight was estimated to be 65,000 by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Bound [‘4C]glycine-labeled al(1) is displaced by unlabeled a1 chain. The binding of [‘“C] glycine-labeled al(I) by the purified al(I) receptor can also be inhibited by the receptor isolated from type I fibrillar collagen-Sepharose affinity chromatography. The data suggest that the al(1) binding site is identical with the type I fibrillar collagen binding site.

Affinity purification of multifunctional polymer nanoparticles

Abstract: We report that multifunctional polymer nanoparticles approximately the size of a large protein can be “purified”, on the basis of peptide affinity just as antibodies, using an affinity chromatography strategy. The selection process takes advantage of the thermoresponsiveness of the nanoparticles allowing “catch and release” of the target peptide by adjusting the temperature. Purified particles show much stronger affinity (Kdapp ≈ nM) and a narrower affinity distribution than the average of particles before purification (Kdapp > μM) at room temperature but can release the peptide just by changing the temperature. We anticipate this affinity selection will be general and become an integral step for the preparation of “plastic antibodies” with near-homogeneous and tailored affinity for target biomacromolecules.

Enrichment and analysis of phosphopeptides under different experimental conditions using titanium dioxide affinity chromatography and mass spectrometry

Abstract: Titanium dioxide metal oxide affinity chromatography (TiO(2)-MOAC) is widely regarded as being more selective than immobilized metal-ion affinity chromatography (IMAC) for phosphopeptide enrichment. However, the widespread application of TiO(2)-MOAC to biological samples is hampered by conflicting reports as to which experimental conditions are optimal. We have evaluated the performance of TiO(2)-MOAC under a wide range of loading and elution conditions. Loading and stringent washing of peptides with strongly acidic solutions ensured highly selective enrichment for phosphopeptides, with minimal carryover of non-phosphorylated peptides. Contrary to previous reports, the addition of glycolic acid to the loading solution was found to reduce specificity towards phosphopeptides. Base elution in ammonium hydroxide or ammonium phosphate provided optimal specificity and recovery of phosphorylated peptides. In contrast, elution with phosphoric acid gave incomplete recovery of phosphopeptides, whereas inclusion of 2,5-dihydroxybenzoic acid in the eluant introduced a bias against the recovery of multiply phosphorylated peptides. TiO(2)-MOAC was also found to be intolerant of many reagents commonly used as phosphatase inhibitors during protein purification. However, TiO(2)-MOAC showed higher specificity than immobilized gallium (Ga(3+)), immobilized iron (Fe(3+)), or zirconium dioxide (ZrO(2)) affinity chromatography for phosphopeptide enrichment. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was more effective in detecting larger, multiply phosphorylated peptides than liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS), which was more efficient for smaller, singly phosphorylated peptides.

Antibody purification: affinity chromatography - protein A and protein G Sepharose.

Abstract: Affinity chromatography relies on the reversible interaction between a protein and a specific ligand immobilized in a chromatographic matrix. The sample is applied under conditions that favor specific binding to the ligand as the result of electrostatic and hydrophobic interactions, van der Waals' forces and/or hydrogen bonding. After washing away the unbound material the bound protein is recovered by changing the buffer conditions to those that favor desorption. The technique has been used not only to isolate antigen-specific antibodies but also to remove specific contaminants from biological samples. Methods are described for the purification of immunoglobulins, namely IgG, IgG fragments and subclasses, using the high affinity of protein A and protein G coupled to agarose. In the Subheading 3 there are also protocols for affinity purification using a specific ligand coupled to commercial matrices like CNBr- Sepharose 4-B and Affigel.

Mutations in maltose-binding protein that alter affinity and solubility properties

Abstract: Maltose-binding protein (MBP) from Escherichia coli has been shown to be a good substrate for protein engineering leading to altered binding (Marvin and Hellinga, Proc Natl Acad Sci U S A 98:4955-4960, 2001a) and increased affinity (Marvin and Hellinga, Nat Struct Biol 8:795-798, 2001b; Telmer and Shilton, J Biol Chem 278:34555-34567, 2003). It is also used in recombinant protein expression as both an affinity tag and a solubility tag. We isolated mutations in MBP that enhance binding to maltodextrins 1.3 to 15-fold, using random mutagenesis followed by screening for enhanced yield in a microplate-based affinity purification. We tested the mutations for their ability to enhance the yield of a fusion protein that binds poorly to immobilized amylose and their ability to enhance the solubility of one or more aggregation-prone recombinant proteins. We also measured dissociation constants of the mutant MBPs that retain the solubility-enhancing properties of MBP and combined two of the mutations to produce an MBP with a dissociation constant 10-fold tighter than wild-type MBP. Some of the mutations we obtained can be rationalized based on the previous work, while others indicate new ways in which the function of MBP can be modified.

Frontal affinity chromatography-mass spectrometry useful for characterization of new ligands for GPR17 receptor.

Abstract: The application of frontal affinity chromatography-mass spectrometry (FAC-MS), along with molecular modeling studies, to the screening of potential drug candidates toward the recently deorphanized G-protein-coupled receptor (GPCR) GPR17 is shown. GPR17 is dually activated by uracil nucleotides and cysteinyl-leukotrienes, and is expressed in organs typically undergoing ischemic damage (i.e., brain, heart and kidney), thus representing a new pharmacological target for acute and chronic neurodegeneration. GPR17 was entrapped on an immobilized artificial membrane (IAM), and this stationary phase was used to screen a library of nucleotide derivatives by FAC-MS to select high affinity ligands. The chromatographic results have been validated with a reference functional assay ([(35)S]GTPgammaS binding assay). The receptor nucleotide-binding site was studied by setting up a column where a mutated GPR17 receptor (Arg255Ile) has been immobilized. The chromatographic behavior of the tested nucleotide derivatives together with in silico studies have been used to gain insights into the structure requirement of GPR17 ligands.

Mycobacterium tuberculosis employs Cpn60.2 as an adhesin that binds CD43 on the macrophage surface.

Abstract: CD43 is a large sialylated glycoprotein found on the surface of haematopoietic cells and has been previously shown to be necessary for efficient macrophage binding and immunological responsiveness to Mycobacterium tuberculosis. Using capsular material from M. tuberculosis and recombinant CD43-Fc, we have employed affinity chromatography to show that Cpn60.2 (Hsp65, GroEL), and to a lesser extent DnaK (Hsp70), bind to CD43. Competitive inhibition using recombinant protein and polyclonal F(ab')(2) antibody-mediated epitope masking studies were used to evaluate M. tuberculosis binding to CD43(+/+) versus CD43(-/-) macrophages. Results showed that Cpn60.2, but not DnaK, acts as a CD43-dependent mycobacterial adhesin for macrophage binding. Assessment of the specific binding between Cpn60.2 and CD43 showed it to be saturable, with a comparatively weak affinity in the low micromolar range. We have also shown that the ability of Cpn60.2 to competitively inhibit M. tuberculosis binding to macrophages is shared by the Escherichia coli homologue, GroEL, but not by the mouse and human Hsp60 homologues. These findings add to a growing field of research that implicates molecular chaperones as having extracellular functions, including bacterial adherence to host cells. Thus, CD43 may act as a Pattern Recognition Receptor (PRR) for bacterial homologues of the 60 kDa molecular chaperone.

Hydroxyapatite affinity chromatography for the highly selective enrichment of mono‐ and multi‐phosphorylated peptides in phosphoproteome analysis

Abstract: The most challenging analytical task facing phosphoproteome determination requires the isolation of phosphorylated peptides from the myriad of unphosphorylated species. In the past, several strategies for phosphopeptide isolation have been proposed in combination with subsequent mass spectrometric investigations. Among these techniques, immobilized metal affinity chromatography and titanium dioxide have been recognized as the most effective. Here, we present an alternative method for the enrichment of phosphopeptides based on hydroxyapatite (HAP) chromatography. By taking advantage of the strong interaction of HAP with phosphate and calcium ions, we developed an efficient method for the selective separation and fractionation of phosphorylated peptides. The effectiveness and efficiency of recovery for this procedure was assayed using tryptic digests of standard phosphorylated protein mixtures. Based on the higher affinity of multi-phosphorylated peptides for HAP surfaces, the introduction of a phosphate buffer gradient for stepwise peptide elution resulted in the separation of mono-, di-, tri-, and multi-phosphorylated peptides. Thus, we demonstrated that this technique is highly selective and independent of the degree of peptide phosphorylation.

Automated Platform for Fractionation of Human Plasma Glycoproteome in Clinical Proteomics

Abstract: This publication describes the development of an automated platform for the study of the plasma glycoproteome. The method consists of targeted depletion in-line with glycoprotein fractionation. A key element of this platform is the enabling of high throughput sample processing in a manner that minimizes analytical bias in a clinical sample set. The system, named High Performance Multi-Lectin Affinity Chromatography (HP-MLAC), is composed of a serial configuration of depletion columns containing anti-albumin antibody and protein A with in-line multilectin affinity chromatography (M-LAC) which consists of three mixtures of lectins concanavalin A (ConA), jacalin (JAC), and wheat germ agglutinin (WGA). We have demonstrated that this platform gives high recoveries for the fractionation of the plasma proteome (≥ 95%) and excellent stability (over 200 runs). In addition, glycoproteomes isolated using the HP-MLAC platform were shown to be highly reproducible and glycan specific as demonstrated by rechromatography...

A highly controllable reconstituted cell-free system--a breakthrough in protein synthesis research.

Abstract: The PURE system is a highly controllable cell-free protein synthesis system composed of individually prepared components that are required for protein synthesis in Escherichia coli. The PURE system contains neither nucleases nor proteases, both of which degrade DNA or mRNA templates and proteins. The protein products are easily purified using affinity chromatography to remove the tagged protein factors. The PURE system should help to create new fields in protein research.

Differential interactions of plasmid DNA, RNA and genomic DNA with amino acid-based affinity matrices

Abstract: The development of a strategy to plasmid DNA (pDNA) purification has become necessary for the development of gene therapy and DNA vaccine production processes in recent years, since this nucleic acid and most of contaminants, such as RNA, genomic DNA and endotoxins, are negatively charged. An ideal separation methodology may be achieved with the use of affinity interactions between immobilized amino acids and nucleic acids. In this study, the binding behaviour of nucleic acids under the influence of different environmental conditions, such as the composition and ionic strength of elution buffer, and the temperature, is compared with various amino acids immobilized on chromatography resins. Supercoiled (sc) plasmid isoform was isolated with all matrices used, but in some cases preferential interactions with other nucleic acids were found. Particularly, lysine chromatography showed to be an ideal technology mainly on RNA purification using low salt concentration. On the other hand, arginine ligands have shown a greater ability to retain the sc isoform comparatively to the other nucleic acids retention, becoming this support more adequate to sc pDNA purification. The temperature variation, competitive elution and oligonucleotides affinity studies also allowed to recognize the dominant interactions inherent to biorecognition of pDNA molecule and the affinity matrices.

Single-step affinity purification for fungal proteomics.

Abstract: A single-step protein affinity purification protocol using Aspergillus nidulans is described. Detailed protocols for cell breakage, affinity purification, and depending on the application, methods for protein release from affinity beads are provided. Examples defining the utility of the approaches, which should be widely applicable, are included.

Synthesis and application of a new cleavable linker for “click”-based affinity chromatography

Abstract: A new chemically-cleavable linker has been synthesised for the affinity-independent elution of biomolecules by classical affinity chromatography. This azo-based linker is shown to couple efficiently with “click” derivatised ligands such as biotin propargyl amide through a copper(I)-catalysed Huisgen 1,3-dipolar cycloaddition reaction. Binding to Affi-Gel matrices displaying ligands coupled to the new linker is both efficient and selective. The captured material may be readily released from the resin upon treatment with sodium dithionite. These mild elution conditions have allowed for the efficient isolation of the affinity partner from complex protein mixtures such as those found in fetal bovine serum.

Cloning, Expression, Purification, and Characterization of Cold-Adapted α-Amylase from Pseudoalteromonas arctica GS230

Abstract: A cold-adapted α-amylase (ParAmy) gene from Pseudoalteromonas arctica GS230 was cloned, sequenced, and expressed as an N-terminus His-tag fusion protein in E. coli. A recombinant protein was produced and purified with DEAE-sepherose ion exchange chromatography and Ni affinity chromatography. The molecular weight of ParAmy was estimated to be 55 KDa with sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE). With an optimum temperature for activity 30 °C, ParAmy showed 34.5% of maximum activity at 0 °C and its activity decreased sharply at above 40 °C. ParAmy was stable in the range of pH 7–8.5 at 30 °C for 1 h. ParAmy was activated by Mn2+, K+ and Na+, and inhibited by Hg2+, Cu2+, and Fe3+. N-Bromosuccinimid showed a significant repressive effect on enzyme activity. The K m and V max values of the α-amylase for soluble starch were 7.28 mg/mL and 13.07 mg/mL min, respectively. This research suggests that Paramy has a good potential to be a cold-stable and alkalitolerant amylase in detergent industry.

Formation of isobutene from 3-hydroxy-3-methylbutyrate by diphosphomevalonate decarboxylase.

Abstract: Isobutene is an important commercial chemical used for the synthesis of butyl rubber, terephthalic acid, specialty chemicals, and a gasoline performance additive known as alkylate Currently, isobutene is produced from petroleum and hence is nonrenewable Here, we report that the Saccharomyces cerevisiae mevalonate diphosphate decarboxylase (ScMDD) can convert 3-hydroxy-3-methylbutyrate (3-HMB) to isobutene Whole cells of Escherichia coli producing ScMDD with an N-terminal 6×His tag (His6-ScMDD) formed isobutene from 3-HMB at a rate of 154 pmol h−1 g cells−1 In contrast, no isobutene was detected from control cells lacking ScMDD His6-ScMDD was purified by nickel affinity chromatography and shown to produce isobutene from 3-HMB at a rate of 133 pmol min−1 mg−1 protein Controls showed that both His6-ScMDD and 3-HMB were required for detectable isobutene formation Isobutene was identified by gas chromatography (GC) with flame ionization detection as well as by GC-mass spectrometry (MS) ScMDD was subjected to error-prone PCR, and two improved variants were characterized, ScMDD1 (I145F) and ScMDD2 (R74H) Whole cells of E coli producing ScMDD1 and ScMDD2 produced isobutene from 3-HMB at rates of 3,000 and 5,888 pmol h−1 g cells−1, which are 19- and 38-fold increases compared to rates for cells producing His6-ScMDD This showed that genetic modifications can be used to increase the rate at which ScMDD converts 3-HMB to isobutene Because 3-HMB can be produced from l-leucine, ScMDD has a potential application for the production of renewable isobutene Moreover, isobutene is a gas, which might simplify its purification from a fermentation medium, substantially reducing production costs

Mapping protein cysteine sulfonic acid modifications with specific enrichment and mass spectrometry: An integrated approach to explore the cysteine oxidation

Abstract: Oxidation of thiol proteins, which results in conversion of cysteine residues to cysteine sulfenic, sulfinic or sulfonic acids, is an important posttranslational control of protein function in cells. To facilitate the analysis of this process with MALDI-MS, we have developed a method for selective enrichment and identification of peptides containing cysteine sulfonic acid (sulfopeptides) in tryptic digests of proteins based on ionic affinity capture using polyarginine-coated nanodiamonds as high-affinity probes. The method was applied to selectively concentrate sulfopeptides from either a highly dilute solution or a complex peptide mixture in which the abundance of the sulfonated analyte is as low as 0.02%. The polyarginine-coated probes exhibit a higher affinity for peptides containing multiple sulfonic acids than peptides containing single sulfonic acid. The limit of the detection is in the femtomole range, with the MALDI-TOF mass spectrometer operating in the negative ion mode. The results show that the new approach has good specificity even in the presence of phosphopeptides. An application of this method for selective enrichment and structural identification of sulfopeptides is demonstrated with the tryptic digests of performic-acid-oxidized BSA.

Thermostable L‐arabinose isomerase from Bacillus stearothermophilus IAM 11001 for D‐tagatose production: gene cloning, purification and characterisation

Abstract: BACKGROUND:D-Tagatose, as one of the rare sugars, has been found to be a natural and safe low-calorie sweetener in food products and is classified as a GRAS substance. L-Arabinose isomerase (L-AI, EC 5.3.1.4), catalysing the isomerisations of L-arabinose and D-galactose to L-ribulose and D-tagatose respectively, is considered to be the most promising enzyme for the production of D-tagatose. RESULTS: The araA gene encoding an L-AI from Bacillus stearothermophilus IAM 11001 was cloned, sequenced and overexpressed in Escherichia coli. The gene is composed of 1491 bp nucleotides and codes for a protein of 496 amino acid residues. The recombinant L-AI was purified to electrophoretical homogeneity by affinity chromatography. The purified enzyme was optimally active at 65 °C and pH 7.5 and had an absolute requirement for the divalent metal ion Mn2+ for both catalytic activity and thermostability. The enzyme was relatively active and stable at acidic pH of 6. The bioconversion yield of D-galactose to D-tagatose by the purified L-AI after 12 h at 65 °C reached 36%. CONCLUSION: The purified L-AI from B. stearothermophilus IAM 11001 was characterised and shown to be a good candidate for potential application in D-tagatose production. Copyright © 2010 Society of Chemical Industry

A lactose specific lectin from the sponge Cinachyrella apion: purification, characterization, N-terminal sequences alignment and agglutinating activity on Leishmania promastigotes.

Abstract: Crude extract from the sponge Cinachyrella apion showed cross-reactivity with the polyclonal antibody IgG anti-CvL (Cliona varians lectin) and also a strong haemagglutinating activity towards human erythrocytes of all ABO groups. Thus, it was submitted to acetone fractionation, IgG anti-deglycosylated CvL Sepharose affinity chromatography, and Fast Protein Liquid Chromatography (FPLC-AKTA Purifier) gel filtration on a Superose 6 10/300 column to purify a novel lectin. C. apion lectin (CaL) agglutinated all types of human erythrocytes with preference for papainized type A erythrocytes. The haemagglutinating activity is independent of Ca2+, Mg2+ and Mn2+ ions, and it was strongly inhibited by the disaccharide lactose, up to a minimum concentration of 6.25 mM. CaL molecular mass, determined by FPLC-gel filtration on a Superose 12 10/300 column and SDS gel electrophoresis, was approximately 124 kDa, consisting of eight subunits of 15.5 kDa, assembled by hydrophobic interactions. The lectin was heat-stable between 0 and 60 degrees C and pH-stable. The N-terminal amino acid sequence of CaL was also determined and a blast search on amino acid sequences revealed that the protein showed similarity only with a silicatein. Leishmania chagasi promastigotes were agglutinated by CaL and this activity was abolished by lactose, indicating that lactose receptors could be presented in this parasite stage. These findings are indicative of the potential biotechnological application of CaL as diagnostic of pathogenic protozoa.

Protein Separation and Characterization Procedures

Abstract: This chapter covers the principles, procedures, and applications of a variety of techniques used to separate and characterize proteins. Separation techniques rely on the differences in the solubility, size, charge, adsorption characteristics of protein molecules. Commonly used protein separation techniques include the following: ion-exchange chromatography, affinity chromatography, dialysis, ultrafiltration, size-exclusion chromatography, electrophoresis [sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing, and capillary electrophoresis]. Proteins can be characterized by their amino acid content, nutritional value, and functional properties. Chromatographic techniques are used to determine the amino acid composition of a protein. The nutritional quality of a protein is determined by its amino acid composition and protein digestibility, measured for nutrition labeling purposes by expensive and time consuming assays, protein digestibility-corrected amino acid score (PDCAAS) or protein efficiency ratio (PER). Other more rapid methods and calculations can be done to assess nutritional value for other purposes. Common tests of protein functionality for a particular food application include solubility, emulsification, foaming, and gelation.