GAMMA RADIOLYSIS OF AMINO ACID AND ENZYME PROTEIN IN DRY POWDER AND IN SOLUTION

Journal Article · Tue Jan 01 04:00:00 EST 1963 · Proc. Japan Conf. Radioisotopes

OSTI ID:4698512

Ganno, S; Ohara, A; Rokushika, S; Murano, M; Hatano, H

After exposure to gamma irradiation as dry powder, twenty amino acids were mixed together and survival amino acids were determined automatically by a new amino acid analyzer, which was designed by H. Hatano and his co-workers in Koyoto University and Hitachi Ltd. When the radiation sensitivity of the amino acids in the state of dry powder was determined, it was found that histidine and tryptophan were relatively radioresistant, and threonine and cystine were radiosensitive under the same condition. In aqueous solution, twenty amino acids were irradiated by gamma rays to produce carbonyl compounds such as corresponding keto acids or aldehydes. Survival amino acids were also deternined by the amino acid analyzer. The radioresistance of tyrosine, contrary to phenylalanine, was due to the resonance structure of the aromatic ring. Trystophan was also found to be radioresistant. The radiosensitivity of sulfurcontaining amino acids was observed in methionine. Constituent amino acids of protein showed different radiolytic behaviors from the above free amino acids. A specimen of bacterial proteinase was exposed to gamma irradiation, and residual proteinous substances were precipitated by addition of a trichloroacetic acid reagent. The precipitate was hydrolyzed according to a usual method and the resultant hydrolysate was subjected to automatic determination of amino acids by the amino acid analyzer. Tyrosine, which is most radioresistant in the state of dry powder, was found to be most radiosensitive when irradiated as one of constituent amino acids of protein. In the dry state no appreciable decrease of the amount of amino acid content of the bacterial proteinase was found after doses of gamma irradiation from 10/sup 3/ r to 10/sup 8/ r. However, the irradiated enzyme had lost about 50 per cent of its proteolytic activity by a dose of 10/sup 7/ r. This fact suggests that some conformational chahge, rather than the chemical structure of the protein, caused the damage to enzyme protein. Electron spin resonance spectra of free radicals produced from the irradiated enzyme were detected by an electron spin resonance spectrometer. (JAIF)

• Research Organization: Kyoto Univ.
• NSA Number: NSA-17-030143
• OSTI ID: 4698512
• Journal Information: Proc. Japan Conf. Radioisotopes, Journal Name: Proc. Japan Conf. Radioisotopes Vol. Vol: 5th, No. 3
• Country of Publication: Country unknown/Code not available
• Language: Japanese

Related Subjects

ACETIC ACID
ALDEHYDES
AMINO ACIDS
CARBONYLS
CYSTEINE
ELECTRONS
ENZYMES
FREE RADICALS
GAMMA RADIATION
GENERAL AND MISCELLANEOUS
HYDROLYSIS
IRRADIATION
ORGANIC CHLORINE COMPOUNDS
PHENYL RADICALS
POWDERS
PRECIPITATION
PROTEINS
QUALITATIVE ANALYSIS
RADIATION DOSES
RADIATION INJURIES
RADIATIONS
RADIOLYSIS
RESONANCE
SENSITIVITY
SOLUTIONS
SPECTRA
SPECTROMETERS
SPIN
WATER