American Journal of Clinical Nutrition, Vol 56, 427-432, Copyright © 1992 by The American Society for Clinical Nutrition, Inc

ORIGINAL RESEARCH COMMUNICATIONS

Distribution of biotin in human plasma: most of the biotin is not bound to protein

DM Mock and MI Malik
Department of Pediatrics, University of Iowa College of Medicine, Iowa City 52242.

Estimates of the plasma concentration of biotin differ considerably. Variation in detectability of biotin bound covalently to protein is one potential source of disagreement. In this study we determined the amount of biotin covalently bound to plasma protein. First, greater than 99% of free and reversibly bound biotin was removed by dialysis; then greater than 90% of covalently bound biotin was released by acid hydrolysis. For plasma samples from 11 normal adults, the ratio of covalently bound biotin to free biotin was 0.15 +/- 0.09 (mean +/- SD). Taking into account the additional biotin that is reversibly bound to protein, this study provides evidence that approximately 12% of total biotin in plasma is covalently bound, 7% is reversibly bound, and 81% is free. We conclude that covalently bound biotin cannot account for the reported sixfold increase in biotin detected after acid hydrolysis. We speculate that the reported increase was an artifact caused by substances produced during acid hydrolysis of plasma.

This article has been cited by other articles:

				D. M. Mock, N. I. Mock, C. W. Stewart, J. B. LaBorde, and D. K. Hansen Marginal Biotin Deficiency Is Teratogenic in ICR Mice J. Nutr., August 1, 2003; 133(8): 2519 - 2525. [Abstract] [Full Text] [PDF]

				D. M Mock, C. L Henrich, N. Carnell, and N. I Mock Indicators of marginal biotin deficiency and repletion in humans: validation of 3-hydroxyisovaleric acid excretion and a leucine challenge Am. J. Clinical Nutrition, November 1, 2002; 76(5): 1061 - 1068. [Abstract] [Full Text] [PDF]

				D. M. Mock and N. I. Mock Lymphocyte Propionyl-CoA Carboxylase Is an Early and Sensitive Indicator of Biotin Deficiency in Rats, but Urinary Excretion of 3-Hydroxypropionic Acid Is Not J. Nutr., July 1, 2002; 132(7): 1945 - 1950. [Abstract] [Full Text] [PDF]

				R. M. Helm, N. I. Mock, P. Simpson, and D. M. Mock Certain Immune Markers Are Not Good Indicators of Mild to Moderate Biotin Deficiency in Rats J. Nutr., December 1, 2001; 131(12): 3231 - 3236. [Abstract] [Full Text] [PDF]

				B. Lewis, S. Rathman, and R. McMahon Dietary Biotin Intake Modulates the Pool of Free and Protein-Bound Biotin in Rat Liver J. Nutr., September 1, 2001; 131(9): 2310 - 2315. [Abstract] [Full Text] [PDF]

				K.-S. Wang, G. L. Kearns, and D. M. Mock The Clearance and Metabolism of Biotin Administered Intravenously to Pigs in Tracer and Physiologic Amounts Is Much More Rapid than Previously Appreciated J. Nutr., April 1, 2001; 131(4): 1271 - 1278. [Abstract] [Full Text]

				J. Hymes and B. Wolf Human Biotinidase Isn't Just for Recycling Biotin J. Nutr., February 1, 1999; 129(2): 485 - 485. [Abstract] [Full Text] [PDF]

				J. Zempleni and D. M. Mock Uptake and metabolism of biotin by human peripheral blood mononuclear cells Am J Physiol Cell Physiol, August 1, 1998; 275(2): C382 - C388. [Abstract] [Full Text] [PDF]

				D. M. Mock, D. D. Stadler, S. L. Stratton, and N. I. Mock Biotin Status Assessed Longitudinally in Pregnant Women J. Nutr., May 1, 1997; 127(5): 710 - 716. [Abstract] [Full Text] [PDF]