PMID: 241414Oct 20, 1975Paper

Enzymic and immunochemical properties of lysozyme. X. Conformation, enzymic activity and immunochemistry of lysozyme reduced at two carboxyl groups

Biochimica Et Biophysica Acta
M Z AtassiA F Habeeb

Abstract

Reduction of lysozyme by diborane, followed by air oxidation of the reduced disulfides and chromatography on CM-cellulose, yielded a homogeneous derivative. In the derivative, the carboxyl groups of aspartic acid 119 and the end-chain leucine residue were reduced to their corresponding alcohols. Correct re-forming of the disulfide bonds was demonstrated by peptide mapping of the tryptic hydrolysates of the derivative and lysozyme without breaking the disulfide bonds, followed by identification of the disulfide-containing peptides. Correct disulfide pairing in the two-disulfide peptide in the tryptic hydrolysate was established from its immunochemical behavior. Preparations of the two-disulfide fragment from lysozyme and derivative had equal inhibitory activities (26 or 32%) of the reaction of lysozyme with two homologous antisera. In ORD measurements, lysozyme and the derivative had equal rotatory powers at neutral pH. However, the bo value for the derivative decreased by about 10%. Below pH 6.4 and above pH 8.0, the derivative was less rotatory than native lysozyme. In CD measurements at neutral pH, the negative ellipticity bands at 220 and 208 nm showed little or no decrease in the derivative relative to the native protein. A...Continue Reading

Related Concepts

Boranes
Circular Dichroism, Vibrational
Disulfides
Egg Whites
Hydrogen-Ion Concentration
Micrococcus
Leftose
Optical Rotatory Dispersion
Oxidation-Reduction
Protein Conformation

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