The Chemical Modification of Proteins by Group-Specific and Site-Specific Reagents

Glazer, Alexander N.

doi:10.1016/b978-0-12-516302-6.50006-2

Cited by 57 publications

(29 citation statements)

References 493 publications

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“…More likely, the cysteine is in close vicinity of the active site and reaction with bulky groups may cause severe steric hindrance. A very attractive explanation would be that formation of a cross-link, either a disulfide bond, by Nbs,, or a -S-Hg-S-structure (Glazer, 1976), may lock the substrate-binding site. Monovalent reagents such as thimerosal, iodoacetamide and MalNEt bind to sulfhydryl groups but do not cross-link them.…”

Section: Discussionmentioning

confidence: 99%

Purification and properties of an α‐methylacyl‐CoA racemase from rat liver

Schmitz

Fingerhut

Conzelmann

1994

European Journal of Biochemistry

106

134

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The (R)-and (S)-isomers of a-methyl-branched fatty acids were shown to be rapidly interconverted as coenzyme A thioesters, by an a-methylacyl-CoA racemase. The enzyme was purified some 5600-fold from rat liver, to apparent homogeneity. It is a monomer of 45 kDa with an isolectric point of pH 6.1 and is optimally active between pH 6 and pH 7. It acts only on coenzyme A thioesters, not on free fatty acids, and accepts as substrates a wide range of a-methylacyl-CoAs, including pristanoyl-CoA and trihydroxycoprostanoyl-CoA (an intermediate in bile acid synthesis), but neither 3-methyl-branched nor linear-chain acyl-CoAs. The racemase catalyzes a rapid exchange of the H atom in the a-position of the fatty acid against a proton from water, indicating that the mechanism involves abstraction of a proton. Based on this observation, a very sensitive and convenient radiometric assay, with 2-methy1[2-3H]acyl-CoAs as substrates, was developed. The enzyme was inactivated by micromolar concentrations of Hg2' and to a lesser extent by Cu2+ but not by iodoacetamide and only slightly by N-ethylmaleimide and thimerosal.

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Section: Discussionmentioning

confidence: 99%

Purification and properties of an α‐methylacyl‐CoA racemase from rat liver

Schmitz

Fingerhut

Conzelmann

1994

European Journal of Biochemistry

106

134

View full text Add to dashboard Cite

show abstract

“…The preceding de tail s more or less fix the configuration of a protei η in a gi ven environment (solvents plus other solutes) which in turn determines its ionization behavior, the number of "exposed" and "buried" groups in it, its overall topology, and the motility of its struc ture (21,36). None of the food proteins subjected to chemical modification heretofore are well defined.…”

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confidence: 99%

Chemical Modification of Food Proteins

Shukla

1982

ACS Symposium Series

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During the past decade, a number of non-conventional proteins have been identified as human food ingredients, e.g., single-cell proteins, fish, leaf, and cereal concentrates, and soybeans, cottonseeds, and rapeseeds. Successful utilization of these new proteinaceous materials depends on their digestibility, nutritive value, and overall functional and organoleptic properties as related to processed food formulations. Many of them, although to varying degrees, fail to meet one or more such utilization criteria.Although the science, much less the art and technology, of chemical modification of food proteins is in its infancy, there exists a potential for the use of existing fundamental knowledge on protein derivatization -modification, replacement, and remov al of amino acid residues, and protein-lipid, protein-carbohy drate, and protein-ligand interactions for commercially viable food products and process research. Such research programs may lead to the development of modified food-grade proteins of improved functionality, nutritive value, and organoleptic quality and of reduced propensity to deterioration by physicochemical agents. This chapter is a review of 1) theory and known mecha nisms of modification, 2) applied and basic research on chemical modification of food proteins, 3) interaction of modified proteins with other food ingredients and 4) legal, regulatory, public health, and consumer acceptance implications of modified food protein products. In general, future research must address three major objectives: 1) selecting a structure-function specific modification scheme; 2) developing a process and product control strategy from commercial standpoints; and 3) testing the efficacy and safety of the product for human consumption. Chemistry of Food Protein ModificationFood protein structure. The knowledge of food protein struc ture, its capacity for covalent and non-covalent interactions, and structure-function relationships in the native state must be 0097-6156/82/0206-0275$07.75/0

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“…Chemical modification reactions on proteins have long been employed in structure-function studies aimed at identifying activesite residues, studying chemical reactivity of specific amino acids, or modifying catalytic properties and proteolytic specificity (Glazer, 1976; Burnens et al, 1987). More recently, acetylation of lysine residues or modification of arginines were used to probe the surface topology of model proteins (Suckau et al, 1992; Glocker et al, 1994) or to investigate interacting regions in protein complexes (Steiner et al, 1991; Ohguro et al, 1994).…”

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confidence: 99%

Surface topology of Minibody by selective chemical modifications and mass spectrometry

et al. 1997

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The surface topology of the Minibody, a small de novo-designed P-protein, has been probed by a strategy that combines selective chemical modification with a variety of reagents and mass spectrometric analysis of the modified fragments. Under appropriate conditions, the susceptibility of individual residues primarily depends on their surface accessibility so that their relative reactivities can be correlated with their position in the tertiary structure of the protein. Moreover, this approach provides information on interacting residues, since intramolecular interactions might greatly affect the reactivity of individual side chains by altering their pKa values.The results of this study indicate that, while overall the Minibody model is correct, the P-sheet formed by the N-and C-terminal segments is most likely distorted. This is also in agreement with previous results that were obtained using a similar approach where mass spectrometry was used to identify Minibody fragments from limited proteolysis (Zappacosta F, Pessi A, Bianchi E, Venturini s, Sollazzo M, Tramontano A, Marino G, Pucci P. 1996. Probing the tertiary structure of proteins by limited proteolysis and mass spectrometry: The case of Minibody. Protein Sci 5902-813). The chemical modification approach, in combination with limited proteolysis procedures, can provide useful, albeit partial, structural information to complement simulation techniques. This is especially valuable when, as in the Minibody case, an NMR and/or X-ray structure cannot be obtained due to insufficient solubility of the molecule.

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The Chemical Modification of Proteins by Group-Specific and Site-Specific Reagents

Cited by 57 publications

References 493 publications

Purification and properties of an α‐methylacyl‐CoA racemase from rat liver

Purification and properties of an α‐methylacyl‐CoA racemase from rat liver

Chemical Modification of Food Proteins

Surface topology of Minibody by selective chemical modifications and mass spectrometry

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