β-하이드록시 β-메틸뷰티릴-CoA(영어: β-hydroxy β-methylbutyryl-CoA, HMB-CoA) 또는 3-하이드록시아이소발레릴-CoA(영어: 3-hydroxyisovaleryl-CoA)는 류신의 대사 과정에서의 대사 중간생성물이며, 인체에서 생성된다. β-하이드록시 β-메틸뷰티릴-CoA(HMB-CoA)는 β-하이드록시 β-메틸뷰티르산(HMB) 및 β-메틸크로토노일-CoA(MC-CoA)의 전구물질이다. β-하이드록시 β-메틸뷰티릴-CoA(HMB-CoA)는 사람에서 β-하이드록시 β-메틸뷰티르산(HMB), β-메틸크로토노일-CoA(MC-CoA) 및 β-하이드록시 β-메틸글루타릴-CoA(HMG-CoA)로 대사될 수 있다.
류신의 대사 경로[편집]
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HMB is a metabolite of the amino acid leucine (Van Koverin and Nissen 1992), an essential amino acid. The first step in HMB metabolism is the reversible transamination of leucine to [α-KIC] that occurs mainly extrahepatically (Block and Buse 1990). Following this enzymatic reaction, [α-KIC] may follow one of two pathways. In the first, HMB is produced from [α-KIC] by the cytosolic enzyme KIC dioxygenase (Sabourin and Bieber 1983). The cytosolic dioxygenase has been characterized extensively and differs from the mitochondrial form in that the dioxygenase enzyme is a cytosolic enzyme, whereas the dehydrogenase enzyme is found exclusively in the mitochondrion (Sabourin and Bieber 1981, 1983). Importantly, this route of HMB formation is direct and completely dependent of liver KIC dioxygenase. Following this pathway, HMB in the cytosol is first converted to cytosolic β-hydroxy-β-methylglutaryl-CoA (HMG-CoA), which can then be directed for cholesterol synthesis (Rudney 1957) (Fig. 1). In fact, numerous biochemical studies have shown that HMB is a precursor of cholesterol (Zabin and Bloch 1951; Nissen et al. 2000).
- Kohlmeier M (May 2015). 〈Leucine〉. 《Nutrient Metabolism: Structures, Functions, and Genes》 2판. Academic Press. 385–388쪽. ISBN 978-0-12-387784-0. 2016년 6월 6일에 확인함.
Energy fuel: Eventually, most Leu is broken down, providing about 6.0kcal/g. About 60% of ingested Leu is oxidized within a few hours ... Ketogenesis: A significant proportion (40% of an ingested dose) is converted into acetyl-CoA and thereby contributes to the synthesis of ketones, steroids, fatty acids, and other compounds
Figure 8.57: Metabolism of L-leucine