ISSN:
1434-4475
Keywords:
Glyceraldehyde-3-phosphate dehydrogenase
;
Lactate dehydrogenase
;
Radiation damage
;
Ribonuclease
;
Serum albumin
;
Small-angle X-ray scattering
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Abstract Measurements carried out withLDH andGAPDH in the presence of 2mM DTT established a strong protective effect ofDTT against the X-ray induced aggregation of these enzymes. The initial increase of $$\tilde R$$ upon irradiation ofLDH andGAPDH in the presence of 2mM DTT was found to be even lower than the increase of $$\tilde R$$ observed when serum albumin was irradiated in the absence ofDTT. However, the observed decrease of $$\bar x$$ ofLDH andGAPDH at the early stages of irradiation suggested the occurrence of fragmentation of the enzymes as another consequence of radiation damage. This finding is discussed in context with the results from previous scattering experiments and electrophoretic studies on malate synthase.
Notes:
Abstract The X-ray induced aggregation of ribonuclease, lactate dehydrogenase (LDH), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and serum albumin in aqueous solution was monitored in situ by means of small-angle X-ray scattering. The time dependence of several molecular parameters viz. the apparent radius of gyration $$\tilde R$$ , the maximum visible diameterD, the mean degree of aggregation $$\bar x$$ , and the mean radius of gyration $$\bar R$$ was used to compare the various proteins with each other and with malate synthase which has been studied previously (P. Zipper andH. Durchschlag, Radiat. and Environm. Biophys., 1980). Measurements carried out with ribonuclease,LDH and serum albumin in the absence of dithiothreitol (DTT) and withGAPDH in the presence of 0.2mM DTT established the following series for the rates of aggregation of the proteins under these conditions: ribonuclease〉LDH〉GAPDH〉serum albumin. The rate of aggregation ofGAPDH was found to be of similar magnitude as that obtained for malate synthase under comparable experimental conditions (presence of 0.2mM DTT, similar X-ray intensity) in our previous study. Within six hours from the beginning of irradiation (i.e. about the time required for the exposure of one complete scattering curve under the conditions of our experiments) the following increases of $$\tilde R$$ resulted: ribonuclease 9%,LDH 7%,GAPDH 4%, serum albumin〈1%. Changes of $$\tilde R$$ exceeding 1% are, of course, too high to be tolerated in conventional scattering experiments.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00899265
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