2-Hydroxy-4-(methylthio) butanoic acid is a naturally occurring methionine precursor in the chick.
The objective of these experiments was to determine the origin of 2-hydroxy-4-(methylthio)-butanoic acid (HMB) detected in the liver and excreta of chicks that had never been fed Alimet (an 88% aqueous solution of HMB) or MHA (an 86% calcium salt of HMB). Gas chromatography and mass spectrometry were used to identify HMB in these birds. A normal biochemical pathway of 5'-deoxy-5'-methylthioadenosine (MTA) is proposed as the source of naturally occurring HMB. Studies of conversion of [methyl-14C]MTA to L-methionine by chick liver enzymesØe showed that radiolabeled HMB and 2-oxo-4-(methylthio)butanoic acid (keto-methionine) were synthesized during the reaction. Specific radioactivities of labeled HMB and keto-methionine showed that HMB is not synthesized from keto-methionine. Fractionation studies indicated that radiolabeled HMB formed from [14C]MTA could be used in the synthesis of L-methionine in the presence of peroxisomes and/or mitochondrial enzymes. In this way, HMB synthesized from MTA by chick liver enzymes functions as a precursor of L-methionine and as an intermediate in a naturally occurring pathway for the synthesis of L-methionine in the chick.
Dibner
J J
JJ
Monsanto Company, Animals Sciences Division, Chesterfield, MO 63198.
Durley
R C
RC
Kostelc
J G
JG
Ivey
F J
FJ
D000241:Adenosine / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D002645:Chickens; D003839:Deoxyadenosines; D008401:Gas Chromatography-Mass Spectrometry; D007700:Kinetics; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000031:analogs & derivatives* / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D013872:Thionucleosides / Q000378:metabolism
D003839:Deoxyadenosines; D013872:Thionucleosides; C008391:alpha-hydroxy-gamma-methylmercaptobutyric acid; C008500:5'-methylthioadenosine; D008715:Methionine; D000241:Adenosine