The effect of solution conditions on bovine serum albumin sulfhydryl reactivity

CP Chee, Richard Owusu-Apenten

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Solution conditions significantly affect sufhydryl (SH) group reactivity of bovine serum albumin (BSA). The objective of this study was to determine the effect of solution conditions on SH-reactivity. Conditions were varied in pH, temperature and the assortment of additives used. Changes in SH-group reactivity, defined in terms of a second order rate constant for SH- disulfide exchange (k, M-1s-1), were measured calorimetrically using 5,5’-dithiobis 2-nitrobenzoate (DTNB2-). All results were compared to BSA under standard conditions (pH 7.0, 50mM ionic strength, 250C). SH-reactivity increased from 0.49 M-1s-1 at pH 6, to 1.74 M-1s-1 at pH 7 and to 14.48 M-1s-1 at pH 8. This increase can be attributed to the pH microenvironment approaching the isoelectric point of cysteine. A 100C increase in temperature from 250C to 350C doubled the rate of SH-group reactivity from 1.74 M-1s-1 to 3.37 M-1s-1. When additives were used, sodium chloride (0.1M) and urea (8M) were found to increase SH-group reactivity from 1.74 M-1s-1 to 23.15 M-1s-1 and 12.03 M-1s-1 respectively; whilst addition of ethanol (10%) did not have any effect on SH-reactivity (k=1.77 M-1s-1). Increase of reactivity upon the addition of sodium chloride (1.0M) may be due to suppression of electrostatic repulsion between BSA and DTNB2-. The increase of SH-group reactivity upon addition of urea is due to the denaturation of BSA’s tertiary structure to expose the hidden SH-group. Findings from this study are important for better understanding of BSA structure and also characterization of SH-group location and reactivity.
Original languageEnglish
Title of host publicationUnknown Host Publication
Place of PublicationChicago, IL
PublisherInstitute of Food Technologists
Number of pages1
Publication statusPublished - 2003
Event2003 IFT Annual Meeting, July 12 - 16, Chicago, IL - Chicago, IL
Duration: 1 Jan 2003 → …

Conference

Conference2003 IFT Annual Meeting, July 12 - 16, Chicago, IL
Period1/01/03 → …

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