Structure-antioxidant activity relationships of flavonoids and phenolic acids

Nanoparticles in a biological fluid (plasma, or otherwise) associate with a range of biopolymers, especially proteins, organized into the "protein corona" that is associated with the nanoparticle and continuously exchanging with the proteins in the environment. Methodologies to determine the corona and to understand its dependence on nanomaterial properties are likely to become important in bionanoscience. Here, we study the long-lived ("hard") protein corona formed from human plasma for a range of nanoparticles that differ in surface properties and size. Six different polystyrene nanoparticles were studied: three different surface chemistries (plain PS, carboxyl-modified, and amine-modified) and two sizes of each (50 and 100 nm), enabling us to perform systematic studies of the effect of surface properties and size on the detailed protein coronas. Proteins in the corona that are conserved and unique across the nanoparticle types were identified and classified according to the protein functional properties. Remarkably, both size and surface properties were found to play a very significant role in determining the nanoparticle coronas on the different particles of identical materials. We comment on the future need for scientific understanding, characterization, and possibly some additional emphasis on standards for the surfaces of nanoparticles.

https://www.pnas.org/content/pnas/105/38/14265.full.pdf

Nanoparticle size and surface properties determine the protein corona with possible implications for biological impacts

基礎講座 電気泳動(Electrophoresis)

The biochemistry and medical significance of the flavonoids.

Obesity and the risk of heart failure

The molecular mechanisms underlying the relationship between low-density lipoprotein (LDL) and the risk of atherosclerosis are not clear. Therefore, detailed information about the protein composition of LDL may contribute to reveal its role in atherogenesis and the mechanisms that lead to coronary disease in humans. Here, we sought to map the proteins in human LDL by a proteomic approach. LDL was isolated by two-step discontinuous density-gradient ultracentrifugation and the proteins were separated with two-dimensional gel electrophoresis and identified with peptide mass fingerprinting, using matrix assisted laser desorption/ionization-time of flight-mass spectrometry and with amino acid sequencing using electrospray ionization tandem mass spectrometry. These procedures identified apo B-100, apo C-II, apo C-III (three isoforms), apo E (four isoforms), apo A-I (two isoforms), apo A-IV, apo J and apo M (three isoforms not previously described). In addition, three proteins that have not previously been identified in LDL were found: serum amyloid A-IV (two isoforms), calgranulin A, and lysozyme C. The identities of apo M, calgranulin A, and lysozyme C were confirmed by sequence information obtained after collision-induced dissociation fragmentation of peptides characteristic for these proteins. Moreover, the presence of lysozyme C was further corroborated by demonstrating enriched hydrolytic activity in LDL against Micrococcus lysodeikticus. These results indicate that in addition to the dominating apo B-100, LDL contains a number of other apolipoproteins, many of which occur in different isoforms. The demonstration, for the first time, that LDL contains calgranulin A and lysozyme C raises the possibility that LDL proteins may play hitherto unknown role(s) in immune and inflammatory reactions of the arterial wall.

Lipoproteomics II: Mapping of proteins in high‐density lipoprotein using two‐dimensional gel electrophoresis and mass spectrometry

A molecular understanding of high-density lipoprotein (HDL) will allow a more complete grasp of its interactions with key plasma remodelling factors and with cell-surface proteins that mediate HDL assembly and clearance. However, these particles are notoriously heterogeneous in terms of almost every physical, chemical and biological property. Furthermore, HDL particles have not lent themselves to high-resolution structural study through mainstream techniques like nuclear magnetic resonance and X-ray crystallography; investigators have therefore had to use a series of lower resolution methods to derive a general structural understanding of these enigmatic particles. This chapter reviews current knowledge of the composition, structure and heterogeneity of human plasma HDL. The multifaceted composition of the HDL proteome, the multiple major protein isoforms involving translational and posttranslational modifications, the rapidly expanding knowledge of the HDL lipidome, the highly complex world of HDL subclasses and putative models of HDL particle structure are extensively discussed. A brief history of structural studies of both plasma-derived and recombinant forms of HDL is presented with a focus on detailed structural models that have been derived from a range of techniques spanning mass spectrometry to molecular dynamics.

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Structure of HDL : particle subclasses and molecular components

The inhibitory effect of the plant flavonoid, rutin, on group I phospholipase A2 (PLA2-I) from porcine pancreas and Naja naja, and on group II phospholipase A2 (PLA2-II) from Vipera russelli and Crotalus atrox was investigated. Rutin efficiently inhibited PLA2-II from both Vipera russelli and Crotalus atrox but was only a weak inhibitor of PLA2-I from porcine pancreas and Naja naja. The lack of strong inhibition of pancreatic PLA2-I was not due to contaminating proteins in the enzyme preparation, since the same weak inhibition was obtained against pancreatic PLA2 purified to homogeneity as judged by two-dimensional gel electrophoresis. Rutin also efficiently inhibited human PLA2-II from synovial fluid but was only a weak inhibitor of human PLA2-I from pancreatic juice, suggesting that rutin is a selective PLA2-I from porcine pancreas. The results obtained indicate that the hydroxyl group in 5-position as well as the double bond and the double-bonded oxygen in the oxane ring are all important for the overall ability of flavonoids to inhibit PLA2 activity, and that the hydroxyl groups in 3'- and 4'- position are required for selective inhibition of PLA2-II.

Flavonoids as phospholipase A2 inhibitors: importance of their structure for selective inhibition of group II phospholipase A2.

There is now significant interest in identifying, quantifying and characterizing the human proteome, and new powerful techniques (proteomics) have evolved to deal with this giant task. In the present study, proteomics have been applied for the first time to map the proteins of the upper airways. The protein contents of human nasal fluid (NLF) and saliva were analysed using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and the proteins were identified by peptide mass fingerprinting using matrix assisted laser desorptioniionization time of night mass spectrometry (MALDI-TOF MS) or by amino acid sequencing using electrospray ionization tandem mass spectrometry (ESI- MS/MS). More than 100 proteins were identified and protein maps of nasal fluid and saliva were thus established. Of particular interest was the identification of a new lipopolysaccharide (LPS)-binding protein, PLUNC (palate lung and nasal epithelial clone), which was shown to be the only protein in NLF that binds to LPS. PLUNC was characterized as multiple isoforms (Mr/p1: 27/5.1, 26/5.2, 25/5.3, 27.5/5.1, 27/5.2, 26/5.3, 25.1/5.5 and 24.8/5.4), and several of these isoforms were demonstrated to be sialylated. Notably, decreased levels of PLUNC were found in NLF of (i) smokers, (ii) epoxy workers with airway irritation, and (iii) patients with seasonal allergic rhinitis (SAR) during allergy season. In addition, the levels of von Ebner's gland protein, α1-antitrypsin, cystatin S, Clara cell protein 16 and lipocortin-1 were altered, either in smokers or SAR patients or both. One previously unidentified NLF protein was found in SAR patients during allergy season but not before season: this protein was identified as eosinophil lysophospholipase. Many of these proteins were post-translationally modified by glycosylation (PLUNC, α1-antitrypsin, von Ebner's gland protein), phosphorylation (cystatin S), acetylation (eosinophil lysophospholipase), or truncation (lipocortin-1). Altogether, these findings illustrate the potential use of proteomics for identifying new markers of upper airway inflammation and for revealing structural details of such markers. The findings also indicate that allergic inflammation in the nasal mucosa is associated with decreased nasal fluid levels of the endogenous proteinase inhibitors, cystatin S and von Ebner's gland protein, and of the new irritation marker, PLUNC. Further studies are required to explore the possibility that PLUNC plays an important part in microbial recognition and that this function is impaired after exposure to airway irritants and during upper airway inflammation.

Mapping of proteins in human saliva using two‐dimensional gel electrophoresis and peptide mass fingerprinting

Human nasal lavage fluids (NLFs) were analyzed with two-dimensional gel electrophoresis (2-DE) and proteins were identified with peptide mass fingerprinting using matrix-assisted laser desoption/ionization time of flight mass spectrometry. In some cases, the identification was verified by analysis of post-source decay fragmentation spectra. Many of the identified proteins were new forms or fragments of previously found proteins (e.g. albumin, lactoferrin, cystatin, calgranulin, von Ebners gland protein and palate lung nasal epithelium clone), while others were proteins that have previously been indicated by 2-DE image matching or immunoblots (e.g. apolipoprotein Al, lysozyme C, and Clara cell secretory protein). Some new proteins, not shown before in 2-DE patterns of NLF were also found, e.g. mammaglobin B, β 2 -microglobulin and immunoglobulin J chain. Of the identified NLF proteins many appear to be involved in inflammatory and immune responses. A study was therefore conducted to investigate if the levels of these proteins were changed in smokers compared to nonsmokers. It was found that NLF from smokers contained decreased levels of Clara cell secretory protein, and increased proportions of a truncated variant of lipocortin-1, three acidic forms of α 1 -antitrypsin, and one phosphorylated form of cystatin S. Furthermore, NLF from smokers contained increased proportions of a new variant of palate lung nasal epithelium clone (PLUNC), a recently identified airway irritation marker. The results demonstrate that 2-DE of NLF may be used to assess alterations of proteins or posttranslationally modified proteins in smokers. Clara cell secretory protein (CC 16, CC 10) and lipocortin-1 are two anti-inflammatory, phospholipase A 2 inhibitory proteins, and α 1 -antitrypsin and cystatin S are two proteinase inhibitors. Changed levels of these proteins may therefore be of importance to the airway inflammation caused by smoking. The results also support the notion that PLUNC is involved in inflammatory responses in the upper airways.

Newly identified proteins in human nasal lavage fluid from non-smokers and smokers using two-dimensional gel electrophoresis and peptide mass fingerprinting.

Mats Lindahl

Papers

Lipoproteomics II: Mapping of proteins in high‐density lipoprotein using two‐dimensional gel electrophoresis and mass spectrometry

Structure of HDL : particle subclasses and molecular components

Flavonoids as phospholipase A2 inhibitors: importance of their structure for selective inhibition of group II phospholipase A2.

Mapping of proteins in human saliva using two‐dimensional gel electrophoresis and peptide mass fingerprinting

Newly identified proteins in human nasal lavage fluid from non-smokers and smokers using two-dimensional gel electrophoresis and peptide mass fingerprinting.