Tissue specificity of the mitochondrial forms of malic enzyme in herring tissues

Abstract

Abstract 1. 1. The activity of malic enzyme per wet weight or per milligram of mitochondrial protein in herring tissues showed significant tissue specificity. 2. 2. The specific activity of herring malic enzyme per mg of mitochondria from testes was 30 times greater than that of malic enzyme found in mitochondria of ovaries. 3. 3. The NAD(P)-dependent mitochondrial malic enzyme was present in all tissues tested and testis mitochondria contained the highest activity of this molecular form. 4. 4. Herring skeletal muscle mitochondria contained nearly identical activities of both molecular forms, the NADP- and NAD(P)-dependent malic enzyme, respectively. 5. 5. The results extend and support the proposal that mitochondria of some fish may contain two molecular forms of malic enzyme and have a unique intramitochondrial pahtway for malate metabolism.