Tissue distribution of carnitine biosynthetic enzymes in man.
The distribution in human tissues of enzymes which convert epsilon-N-trimethyl-L-lysine to L-carnitine was studied. Existing methodology was modified and new procedures were developed to measure enzyme activities. Epsilon-N-Trimethyl-L-lysine was converted to gamma-butyrobetaine in three enzymatic steps (hydroxylation at carbon 3, aldol cleavage between carbons 2 and 3 to yield glycine and gamma-trimethylaminobutyraldehyde, and subsequent oxidation of the aldehyde) in all tissues studied (liver, brain, kidney, heart and skeletal muscle), but gamma-butyrobetaine was hydroxylated to form L-carnitine only in liver, kidney and brain. Gamma-Butyrobetaine hydroxylase (4-trimethylaminobutyrate, 2-oxoglutarate: oxygen oxidoreductase (3-hydroxylating), EC 1.14.11.1) activity in liver was dependent on the age of the subject. The activity rose from 12% in infants to 100% of the adult mean by age 15 years. No age dependence could be demonstrated for the other three enzymes studied.
D000293:Adolescent; D000328:Adult; D000375:Aging; D000444:Aldehyde Dehydrogenase; D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D000446:Aldehyde-Lyases / Q000378:metabolism*; D002331:Carnitine / Q000096:biosynthesis*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005965:Glucuronates / Q000378:metabolism; D006801:Humans; D007223:Infant; D007700:Kinetics; D007783:Lactones / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009928:Organ Specificity; D014018:Tissue Distribution; D050563:gamma-Butyrobetaine Dioxygenase
D005965:Glucuronates; D007783:Lactones; C003712:trimethyllysine; D006899:Mixed Function Oxygenases; C025931:trimethyl-lysine hydroxylase; D050563:gamma-Butyrobetaine Dioxygenase; D000445:Aldehyde Oxidoreductases; D000444:Aldehyde Dehydrogenase; D000446:Aldehyde-Lyases; C025594:beta-hydroxy-trimethyllysine aldolase; D008239:Lysine; D002331:Carnitine