Tryptophan at position 104 is involved in transforming light signal into changes of beta-sheet structure for the signaling state in the BLUF domain of AppA

AppA is a member of an FAD-based new class blue-light sensory protein known as sensor of blue light using FAD (BLUF) protein. The spectroscopic properties of an AppA BLUF domain (AppA126), in which the tryptophan residue at position 104 had been replaced with alanine (W104A), were characterized. The W104A mutant AppA126 showed a nearly normal absorption red shift in the FAD UV-visible absorption upon illumination; however, the light state relaxed to the dark state at a rate approximately 150 times faster than that of wild-type AppA126. Light-induced structural changes of FAD and apoprotein in the wild-type and mutant AppA126 were studied by means of light-induced Fourier transform infrared (FTIR) difference spectroscopy using AppA126, in which the apoprotein had been selectively labeled with 13C. The light-induced FTIR spectrum of the W104A mutant AppA126 revealed bands corresponding to a C4 = O stretch of the FAD isoalloxazine ring and structural changes of apoprotein, but with some alterations in the bands' features. Notably, however, prominent protein bands at 1,632(+)/1,619(-) cm(-1) caused by changes in the beta-sheet structure were eliminated by the mutation, indicating that Trp104 is responsible for transforming the light signal into a specific beta-sheet structure change in the apoprotein of the AppA BLUF domain in the signaling state.     

Transgenic studies of alpha(1)-adrenergic receptor subtype function

Mice with altered alpha(1)-adrenergic receptor (AR) genes have become important tools in elucidating the subtype-specific functions of the three alpha(1)-AR subtypes because of the lack of sufficiently subtype-selective pharmacological agents. Mice with a deletion (knockout, KO) or an overexpression (transgenic, TG) of the alpha(1A)-, alpha(1B)-, or alpha(1D)-AR subtypes have been generated. The alpha(1)-ARs are the principal mediators of the hypertensive response to alpha(1)-agonists in the cardiovascular system. Studies with these mice indicate that alpha(1A)-AR and alpha(1B)-AR subtypes play an important role in cardiac development and/or function as well as in blood pressure (BP) response to alpha(1)-agonists via vasoconstriction. The alpha(1B)- and alpha(1D)-subtypes also appear to be involved in central nervous system (CNS) processes such as nociceptive responses, modulation of memory consolidation and working memory. The ability to study subtype-specific functions in different mouse strains by altering the same alpha(1)-AR in different ways strengthens the conclusions drawn from these studies. Although these genetic approaches have limitations, they have significantly increased our understanding of the functions of alpha(1)-AR subtypes.     

Flavanols,as Plant Growth Inhibitors from Roots of Peach,Prunus persica Batsh. cv. ‘Hakuto ’

Three flavanols, which inhibit root growth in the rice seedling test, have been purified. One was (+)-afzelechin (1) and the other two, named Pia and PIb, were new biflavanols shown by the structures 2 and 3 on the basis of chemical and spectroscopic evidence. PIa inhibited the root growth of the peach seedlings. In addition, PIa was found in the soil in the area where the peach trees were growing. The flavanols, therefore, are suggested to be one of the chemical factors causing soil sickness often encountered in peach cultivation.     

Studies on Plant Growth Substances

1-Naphthoic acid derivatives substituted with chlorine, bromine, methyl or nitro groups at various positions of the ring were assayed for their activities in the pea straight-growth and the callus formation tests. Their growth activities are discussed from two points of view, i.e. the spatial structure hypothesis of Veldstra and the ortho reaction hypothesis advanced for benzoic acid derivatives proposed by Hansch and Muir. It appears that a combination of these two views are appropriate for the present authors’ results.     

Synthesis and Comparative Cytokinin Activities of N-(Purin-6-yl)-d- and -l-amino Acid Methyl Esters

Six pairs of enantiomeric N-(purin-6-yl)amino acid methyl esters were synthesized and tested for their cytokinin activities by three bioassay systems, the growth of tobacco callus, the seed germination of lettuce and the fresh weight increase of excised radish cotyledons.l-(—)-Antipodes were as a whole more active than the corresponding d-(+)-isomers in the tobacco callus and seed germination tests, whereas an uniform tendency was not observed in the radish cotyledon expansion. The discussions were focused on the effects on the biological response of configurational arrangements around the asymmetric center at α-position to the adenine ring and on species difference of cytokinin receptor molecules.     

Isolation of a New Cytokinin from Immature Yellow Lupin Seeds

A new cytokinin was isolated from methanol extracts of immature lupin seeds (Lupinus luteus) through successive purification of charcoal adsorptions, silver precipitations, ion exchange and paper chromatography. The structure was confirmed by spectral data and synthesis as (?)-6-N-(4-hydroxy-3-methylbutylamino)purine, (?)-dihydrozeatin (I).