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The effect of solution conditions on bovine serum albumin sulfhydryl reactivity

Chee, CP and Owusu-Apenten, Richard (2003) The effect of solution conditions on bovine serum albumin sulfhydryl reactivity. In: 2003 IFT Annual Meeting, July 12 - 16, Chicago, IL, Chicago, IL. IFT. 1 pp. [Conference contribution]

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URL: http://ift.confex.com/ift/2003/techprogram/paper_19760.htm

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.

Item Type:Conference contribution (Poster)
Faculties and Schools:Faculty of Life and Health Sciences > School of Biomedical Sciences
Faculty of Life and Health Sciences
Research Institutes and Groups:Biomedical Sciences Research Institute > Nutrition Innovation Centre for Food and Health (NICHE)
Biomedical Sciences Research Institute
ID Code:24454
Deposited By: Dr Richard Owusu-Apenten
Deposited On:09 Jan 2013 11:11
Last Modified:09 Jan 2013 11:11

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