Artificial neural networks: fundamentals, computing, design, and application

During the past 15 years, the methylotrophic yeast Pichia pastoris has developed into a highly successful system for the production of a variety of heterologous proteins. The increasing popularity of this particular expression system can be attributed to several factors, most importantly: (1) the simplicity of techniques needed for the molecular genetic manipulation of P. pastoris and their similarity to those of Saccharomyces cerevisiae, one of the most well-characterized experimental systems in modern biology; (2) the ability of P. pastoris to produce foreign proteins at high levels, either intracellularly or extracellularly; (3) the capability of performing many eukaryotic post-translational modifications, such as glycosylation, disulfide bond formation and proteolytic processing; and (4) the availability of the expression system as a commercially available kit. In this paper, we review the P. pastoris expression system: how it was developed, how it works, and what proteins have been produced. We also describe new promoters and auxotrophic marker/host strain combinations which extend the usefulness of the system.

http://www.biotechlab.ch/UserFiles/File/787339_Ref_CererghinoCregg2000.pdf

Heterologous protein expression in the methylotrophic yeast Pichia pastoris

Natural antioxidants from residual sources.

https://digital.csic.es/bitstream/10261/63157/4/Gomez-Guillen-collagenreview_CSIC.pdf

Functional and bioactive properties of collagen and gelatin from alternative sources: A review

Pectin is an important polysaccharide with applications in foods, Pharmaceuticals, and a number of other industries. Its importance in the food sector lies in its ability to form gel in the presence of Ca2+ ions or a solute at low pH. Although the exact mechanism of gel formation is not clear, significant progress has been made in this direction. Depending on the pectin, coordinate bonding with Ca2+ ions or hydrogen bonding and hydrophobic interactions are involved in gel formation. In low‐methoxyl pectin, gelation results from ionic linkage via calcium bridges between two carboxyl groups belonging to two different chains in close contact with each other. In high‐methoxyl pectin, the cross‐linking of pectin molecules involves a combination of hydrogen bonds and hydrophobic interactions between the molecules. A number of factors—pH, presence of other solutes, molecular size, degree of methoxylation, number and arrangement of side chains, and charge density on the molecule— influence the gelation o...

Chemistry and uses of pectin--a review.

Hydrophobicity determined by a fluorescence probe method and its correlation with surface properties of proteins

SULFHYDRYL (SH) and disulfide (SS) groups have been widely implicated as im­ portant functional groups in many food proteins. The formation of {3-lactoglobu­ lin-K-casein complexes when milk is heated may occur through the SS inter­ change reaction (Sawyer, 1969 ). The thick gel of egg white is considered to consist of large glycoprotein molecules crosslinked by SS bonds and a reductive mechanism has been proposed to explain the thinning reaction which occurs on ag­ ing of eggs (Shenstone, 1968). Further, it is well documented that addition of SH compounds to flour drastically weakens the rheological properties of the flour (Kuninori and Sullivan, 1968 ). Interac­ tions between SS and SH groups of flour have been suggested to explain, in part, this change. A simple method for the measurement of SH and SS groups in foods would clearly be desirable. Assay procedures utilizing Ellman's reagent (Ellman, 19 59) have the advantage of being simple, rapid and direct (Kalab, 1970) and have yielded values comparable with other analytical methods for SH groups (Fernandez-Diez et al., 1964) and for SS groups (Atassi et al., 1970) in purified proteins. In this report a method for the deter­ mination of both SH and SS groups utiliz­ ing Ellman's reagent is applied to flour, egg white, milk and their products.

Determination of sh- and ss-groups in some food proteins using ellman's reagent

A database consisting of 168 dipeptides and 140 tripeptides was constructed from published literature to study the quantitative structure−activity relationships of angiotensin I-converting enzyme (ACE) inhibitory peptides. Two models were computed using partial least squares regression based on the three z-scores of 20 coded amino acids and further validated by cross-validation and permutation tests. The two-component model could explain 73.2% of the Y-variance (inhibitor concentration that reduced enzyme activity by 50%, IC50) with the predictive ability of 71.1% for dipeptides, while the single-component model could explain 47.1% of the Y-variance with the predictive ability of 43.3% for tripeptides. Amino acid residues with bulky side chains as well as hydrophobic side chains were preferred for dipeptides. For tripeptides, the most favorable residues for the carboxyl terminus were aromatic amino acids, while positively charged amino acids were preferred for the middle position, and hydrophobic amino ac...

https://www.genscript.com/site2/document/1329_20060221201229.PDF

Structural Requirements of Angiotensin I-Converting Enzyme Inhibitory Peptides: Quantitative Structure−Activity Relationship Study of Di- and Tripeptides

Protein hydrophobicity of 42 native and partially denatured milk and soy protein samples was determined fluorometrically by using three probes, 1-anilino-8-naphthalenesulfonate (ANS), cis-parinarate (CPA) and 1,6-diphenyl hexatriene (DPH), and chromatographically by using Phenyl Sepharose CL-4B (PSC). PSC and ANS hydro- phobicities correlated well to the protein insolubility determined at zero zeta potential, whereas no significant correlation was observed between CPA. hydrophobicity and protein insolubility. When backwards stepwise regression analysis was applied to 189 data of protein insolubility, a significant correlation (P < 0.001) was obtained between PSC hydrophobicity, zeta potential and protein insolubility. It is suggested that the aromatic hydrophobicity, in conjunction with zeta potential, may play a more important role in protein solublity than the aliphatic hydrophobicity.

Shuryo Nakai

Papers

Hydrophobicity determined by a fluorescence probe method and its correlation with surface properties of proteins

Determination of sh- and ss-groups in some food proteins using ellman's reagent

Structural Requirements of Angiotensin I-Converting Enzyme Inhibitory Peptides: Quantitative Structure−Activity Relationship Study of Di- and Tripeptides

Relationships of Hydrophobicity and Net Charge to the Solubility of Milk and Soy Proteins

Structure-function relationships of food proteins: with an emphasis on the importance of protein hydrophobicity