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[33] Turnover of protein-bound lipoic acid

1979; Academic Press; Linguagem: Inglês

10.1016/0076-6879(79)62213-9

1557-7988

Franklin R. Leach,

Alcoholism and Thiamine Deficiency

This chapter discusses the turnover of protein-bound lipoic acid. Abnormal proteins turn over faster than normal ones; those of larger size are degraded faster than smaller ones, and those enzymes that are important in control turn over faster than the enzymes that do not regulate. There are proteolytic enzymes that specifically degrade enzymes containing a specific prosthetic group. Many enzymes are regulated by the covalent modifications of specific groups. A more economical way of regulation involves the turnover of covalently bound cofactors. The chapter also explains the existence of the required enzymes for attaching and removing vitamins. In mammals, the pyruvate dehydrogenase complex contains two regulating enzymes, a kinase and a phosphatase; while in bacterial systems, the regulation is by product inhibition and feedback regulation by nucleotides.