Lipoamidase activity in human serum is due to biotinidase.

Abstract

Lipoamidase, as determined by lipoyl-p-aminobenzoic acid (L-pABA) hydrolyzing activity, and biotinidase in human serum have similar pH profiles, molecular weights, thermostabilities, and are similarly inhibited by p-hydroxymercuribenzoate and not inhibited by phenylmethylsulfonylfluoride. A monospecific polyclonal antibody prepared against biotinidase immunoprecipitated greater than 95% of serum L-pABA hydrolyzing activity and an identical proportion of biotinidase activity. In addition, children with profound biotinidase deficiency (less than 10% normal serum activity) have greatly reduced levels of L-pABA hydrolyzing activity in serum (less than 15% of mean normal activity) and obligate heterozygotes have activities intermediate between that of normal and profoundly deficient individuals. These results indicate that most, if not all, of the L-pABA hydrolyzing activity in human serum is due to biotinidase. Moreover, since the Km of L-pABA hydrolysis by serum is high, it is unlikely that lipoic acid is recycled in the serum by biotinidase.

• Authors: C L Garganta, B Wolf
• Journal: Clinica chimica acta; international journal of clinical chemistry (Clin Chim Acta) Vol. 189 Issue 3 Pg. 313-25 (Aug 31 1990) ISSN: 0009-8981 [Print] Netherlands
• PMID: 2225462 (Publication Type: Comparative Study, Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Aminobenzoates
• Hydroxymercuribenzoates
• para-Aminobenzoates
• lipoyl-4-aminobenzoic acid
• 4-hydroxymercuribenzoate
• N-biotinyl-4-aminobenzoic acid
• Phenylmethylsulfonyl Fluoride
• Biotin
• Thioctic Acid
• Amidohydrolases
• lipoamidase
• Biotinidase
• 4-Aminobenzoic Acid

Topics

• 4-Aminobenzoic Acid (blood)
• Amidohydrolases (blood, metabolism)
• Aminobenzoates
• Biotin (analogs & derivatives, blood)
• Biotinidase
• Chromatography, Gel (methods)
• Enzyme Stability
• Hot Temperature
• Humans
• Hydrogen-Ion Concentration
• Hydrolysis
• Hydroxymercuribenzoates (pharmacology)
• Kinetics
• Milk, Human (enzymology, metabolism)
• Molecular Weight
• Phenylmethylsulfonyl Fluoride (pharmacology)
• Thioctic Acid (analogs & derivatives, blood)
• para-Aminobenzoates