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DNA photolyase purified from baker's yeast by affinity chromatography on UV-irradiated DNA noncovalently bound to cellulose and by chromatography on activated thiol-Sepharose 4B yields a single protein band having a molecular weight of 51 000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weight, 53 000, determined by gel filtration was in good agreement. Upon denaturation of photolyase by heat or 8 M urea, flavin adenine dinucleotide (oxidized) was isolated from the mixture and identified by thin-layer chromatography and spectral analysis. In contrast to flavoproteins to which flavin adenine dinucleotide (oxidized) is bound which generally exhibit two absorbance maxima between 300 and 500 nm, photolyase has only one at 380 nm. These findings and the similar characteristics of the absorbance and emission spectra of native photolyase with those of flavoproteins in which the chromophore is considered to be the 4a,5-reduced flavin have led us to propose this configuration for the photolyase chromophore. The difference in properties of yeast photolyase compared to the one reported previously supports the idea that there are two photolyases in baker's yeast.

When cassava (Mauihet escadeta Crantz) root was cut into blocks and incubated under laboratory conditions, the blocks showed more widespread and more even symptoms of physiological deterioration than those under natural conditins. Thus, the tissue block system has potental for bio- (12)(13)(14). The deterioration consists of two types. The first is physiological deterioration characterized by internal root discoloration. The second is microbial deterioration caused largely by a wound pathogen (1). The mechanism and cause of the deterioration, however, have not yet been elucidated thoroughly.Under natural conditions, the roots show rather local and spotted deterioration symptoms and that has hindered biochemical studies. In the present study, we cut the cassava root into blocks and incubated them under laboratory conditions. The blocks showed more widespread and more even physiological deterioration symptoms than those under natural conditions, indicating the potential for biochemical study of deterioration.Cassava is a cyanogenic plant and contains linamarin (isobu-tyronitrile-i-r-glucoside) as a main component (2). In this paper,we investigated the changes in cyanide content and linamarase (linamarin fl-D-glucoside glucohydrolase; EC 3.2.1.21) activity

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