Measurements of half-life of rat cardiac myosin heavy chain with Leucyl-tRNA used as precursor pool. [/sup 3/H tracer technique]
The kinetics of labeling of myosin heavy chain, following a single intravenous injection of L-(4,5-/sup 3/H)leucine, were analyzed with the help of a computer, in conjunction with the labeling kinetics of the specific radioactivities of the precursor amino acid pool. As precursor we used leucyl-tRNA which, as we show here, differs significantly from the intracellular free leucine pool. The half-life of myosin heavy chain was determined from the initial period (0 to 60 min) of incorporation of label into protein after a single injection of tritiated leucine, and also from the period (7 to 14 days) when there is exponential decay of the labeled protein. Myosin heavy chain was separated from other myofibrillar proteins by polyacrylamide gel electrophoresis before measurement of leucine specific radioactivity. The specific radioactivity was measured in both protein and precursor pools by a sensitive isotope dilution procedure (range, 100 to 1500 pmol). The values for the half-life of myosin heavy chain determined at both intervals were similar (5.4 and 5.9 days). Substitution of the specific radioactivity of the intracellular free leucine pool decreased the half-life to 2.7 days. Similar values were obtained when the half-life was calculated by simple graphical integration of the experimental curves.
- Research Organization:
- Univ. of Chicago
- OSTI ID:
- 7306885
- Journal Information:
- J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 252:10; ISSN JBCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL HALF-LIFE
BODY
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
COMPUTERS
GLOBULINS
HEART
HYDROGEN ISOTOPES
ISOTOPES
LABELLING
LEUCINE
LIGHT NUCLEI
MAMMALS
METABOLISM
MOLECULAR STRUCTURE
MYOSIN
NUCLEI
NUCLEIC ACIDS
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RATS
RNA
RODENTS
TRITIUM
VERTEBRATES
YEARS LIVING RADIOISOTOPES