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An inhibitor from Pinus radiata was separated using paper chromatography from an acidic ether fraction of a stem tissue extract. Using electrophoresis the inhibitory activity was resolved into two parts. One part remained at the origin. The second part behaved similarly to ABA, in electrophoresis and was investigated further. The inhibitor has similar properties to ABA in electrophoresis; TLC using a number of solvent systems; UV fluorescence spectra: UV absorption; ORD spectra and gas chromatography. Final proof of the identity of the natural inhibitor as ABA was obtained by gas chromatography-mass spectrometry. [ABSTRACT FROM AUTHOR]

The thiobarbituric acid reacting material produced during enzymatic microsomal lipid peroxidation has been identified as malonaldehyde. The malonaldehyde was condensed with urea to form 2-hydroxy-pyrimidine, which was identified by its ultraviolet spectrum, chromatographic properties, and mass spectrum. Incubations with phosphatidyl choline labelled with tritiated arachidonate yielded 2-hydroxy-pyrimidine with a specific activity nearly equal to that of the phospholipid arachidonate. Incubations with tritiated arachidonic acid yielded 2-hydroxy-pyrimidine with a specific activity nearly 2 orders of magnitude less than that of free arachidonic acid. Therefore, phospholipid arachidonate has been established as the major source of the malonaldehyde produced during microsomal lipid peroxidation. [ABSTRACT FROM AUTHOR]

The ultraviolet spectral change at 245 nm of tyrosine residues in histones in alkaline solution was studied. The difference spectrum of histones between alkaline and neutral solution yields an absorption maximum at 242 nm. However, the influence of configurational changes of backbone structure of histones in alkaline solution, results in the true peak position being located near 245 nm. This was established from artificial difference spectra between histones and N-acetyl-L-tyrosine ethyl ester in 0.5 N NaOH, conditions under which ionization of phenolic hydrogens of histones is immediately complete. This ease of ionization permits the quantitative estimation of histones in nucleohistone by measuring the ratio of absorbance at 244 nm to that at 260 nm. so long as we can prepare the nucleohistone from calf thymus which does not contain nonhistone protein. Alkaline spectrophotometric titration of nucleohistone revealed that conformational changes of histones occur when the double helical structure of DNA is in the process of disruption in a nucleohistone molecule. This conformational change occurred without the dissociation of histones and DNA. The dissociation of histones and DNA in alkaline pH region was discussed. [ABSTRACT FROM AUTHOR]