Pyruvate kinase and alanine synthesis in skeletal muscle.
L-Phenylalanine is an allosteric inhibitor of M1-type pyruvate kinase. Accordingly, the effects were studied of 20 mM phenylalanine on the metabolism of 5 mM [U-14C]glucose and 3 mM L-[U-14C]glutamate by isolated hemidiaphragms from starved rats. Phenylalanine inhibited lactate and 14CO2 production from both substrates and stimulated alanine release. It is concluded that pyruvate kinase may have a dual role in intermediary metabolism in skeletal muscle: the enzyme is a component of the lower glycolytic pathway and is implicated in a pathway of amino acid oxidation and alanine synthesis.
D000409:Alanine / Q000096:biosynthesis*; D000818:Animals; D002250:Carbon Radioisotopes; D003964:Diaphragm / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D007700:Kinetics; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010649:Phenylalanine / Q000494:pharmacology; D011770:Pyruvate Kinase / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation
D002250:Carbon Radioisotopes; D005971:Glutamates; D018698:Glutamic Acid; D010649:Phenylalanine; D011770:Pyruvate Kinase; D005947:Glucose; D000409:Alanine