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Methylmalonyl Coenzyme A mutase, also known as MCM is an enzyme that catalyzes the isomerization of methylmalonyl-CoA to succinyl-CoA and it is involved in key metabolic pathways. It requires a -derived prosthetic group, adenosylcobalamin (commonly referred to as AdoCbl), to function. Methylmalonyl-CoA mutase was first identified in rat liver and sheep kidney in 1955. In its latent form, it is 750 amino acids in length. Upon entry to the mitochondria, the 32 amino acid mitochondrial leader sequence at the N-terminus of the protein is cleaved, forming the fully processed monomer. The monomers then associate into homodimers, and bind AdoCbl (one for each monomer active site) to form the final, active holoenzyme form. The processing protein, ''MMAA'' protein, fills the important role of aiding cofactor loading and exchange. ''MMAA'' protein favors association with the MCM apoenzyme, and allows for the transfer of the AdoCbl cofactor to the enzyme active site.〔 Furthermore, if the bound AdoCbl accrues oxidative damage during normal functioning, ''MMAA'' protein fosters exchange of the damaged cofactor for a new AdoCbl via a GTP-reliant pathway.〔〔 Methylmalonyl-CoA mutase is expressed in high concentrations in the kidney, in intermediate concentrations in the heart, ovaries, brain, muscle, and liver, and in low concentrations in the spleen.〔 The enzyme can be found all throughout the central nervous system (CNS).〔 ==Function== Methylmalonyl-CoA mutase catalyzes the following reaction: The substrate of methylmalonyl-CoA mutase, methylmalonyl-CoA, is primarily derived from propionyl-CoA, a substance formed from the catabolism and digestion of isoleucine, valine, threonine, methionine, thymine, cholesterol, or odd-chain fatty acids. The product of the enzyme, succinyl-CoA, is a key molecule of the TCA cycle. MCM resides in the mitochondria, where a number of substances, including the branched-chain amino acids isoleucine and valine, as well as methionine, threonine, thymine and odd-chain fatty acids, are metabolized via methylmalonate semialdehyde (MMlSA) or propionyl-CoA (Pr-CoA) to a common compound - methylmalonyl-CoA (MMl-CoA). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Methylmalonyl-CoA mutase」の詳細全文を読む スポンサード リンク
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