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Biomedical subjects

K Shibata

Publications and source records attributed to K Shibata.

At least 811 records · Page 45Linked to original sources
PubMed1976

Chlorophyll and peptide compositions in the two photosystems of marine green algae.

The molar ratios of chlorophyll a to b in the thalli of marine green algae were between 1.5 and 2.2, being appreciably lower than the ratio between 2.8 and 3.4 found for the leaves of higher plants and the cells of fresh-water green algae. The ratio of chlorophylls to P-700 in these marine algae was also lower than that in higher plants. The a/b ratios in the pigment proteins of Photosystems 1 and 2 separated by polyacrylamide-gel electrophoresis from sodium dodecyl sulfate-solubilized chloroplasts of four species of marine green algae, Bryopsis maxima, Cheatomorpha spiralis, Enteromorpha compressa and Ulva conglobata, were approximately 5 and 1, which are considerably smaller than the ratios, 7 and 2, respectively, found for the pigment proteins of the two photosystems of higher plants separated by the same technique. The chloroplasts of Bryopsis maxima and Cheatomorpha spiralis lacked two of the peptides associated with Photosystem II, which are present in the chloroplasts of Spinacia oleracea and Taraxacum officinale.

Binding Sites↗
PubMed1976

Inhibitory effect of p-nitrothiophenol in the light on the photosystem II activity of spinach chloroplasts.

The treatment of spinach chloroplasts with p-nitrothiophenol in the light at acidic and neutral pH'S caused specific inhibition of the Photosystem II activity, whereas the same treatment in the dark did not affect the activity at all. The photosystem I activity was not inhibited by p-nitrothiophenol both in the light and in the dark. The inhibition was accompanied by changes of fluorescence from chloroplasts. As observed at room temperature, the 685-nm band was lowered by the p-nitrothiophenol treatment in the light and, at liquid nitrogen temperature, the relative height of the 695-nm band to the 685-nm band increased and the 695-nm band shifted to longer wavelengths. The action spectra for these effects of p-nitrothiophenol on the activity and fluorescence showed a peak at 670 nm with a red drop at longer wavelengths. It was concluded that the light absorbed by Photosystem II is responsible for the chemical modification of chloroplasts with p-nitrothiopehnol to causing the specific inhibition of Photosystem II.

2,6-Dichloroindophenol↗
PubMed1976

Developmental studies on glucosamine metabolism.

Changes in hepatic hexosamine metabolism and serum seromucoid concentrations during postnatal development were investigated in the rat. A relatively low activity of hepatic L-glutamine: D-fructose-6-phosphate aminotransferase (AT) was observed within 24 hr of birth. This rapidly increased to a maximum at about 2 weeks of age, followed by a decline to adult levels after another 2 weeks. The developmental pattern of hepatic UDP-N-acetylglucosamine 2'-epimerase (EP) closely resembled that of AT. It was relatively low in the newborn, increased to a maximum at about 2 weeks and then declined to adult values after another 2 weeks. The serum seromucoid concentration was low in the new born rats and then increased gradually with development to adult levels at about 50 days. The hepatic concentrations of UDP-GlcNAC and CMP-NANA both were relatively high at 24 hr after birth compared to values observed at 50 days. The developmental pattern observed for both over this time period was quite similar and was almost the reciprocal to that for the seromucoid fraction. After 50 days the concentration of UDP-GlcNAc remained constant at adult levels as did that of the seromucoid fraction, but the concentration of CMP-NANA showed a marked increase. It is suggested that the hepatic concentrations of these amino-sugar nucleotides during development primarily reflect the demand for the hepatic synthesis and secretion of plasma glycoproteins as reflected in the seromucoid fraction.

Aging↗
PubMed1975

Characteristics of thermoluminescence bands of intact leaves and isolated chloroplasts in relation to the water-splitting activity in photosynthesis.

Plant materials (intact leaves, chloroplasts or subchloroplast particles) pre-illuminated at a low temperature (e.g. -60 degrees C) were rapidly cooled to -196 degrees C and then the luminescence emitted from the sample on raising the temperature was measured as a function of temperature, by means of a sensitive photo-electron counting technique. Mature spinach leaves showed five luminescence bands at different temperatures which were denoted as ZV, A, B1, B2 and C bands. The A, B1, B2 and C bands appeared at constant temperatures, -10, +25, +40 and +55 degrees C, respectively, being independent of the illumination temperature, but the ZV band appeared at a variable temperature slightly higher than the illumination temperature. The B1 and B2 bands were absent in the thermoluminescence profiles of samples devoid of the oxygen-evolving activity, such as heat-treated spinach leaves, wheat leaves greened under intermittent illumination and photosystem-II particles prepared with Triton X-100. It was deduced that these luminescence bands arise from the energy stored by the electron flow in photosystem II to evolve oxygen, and other bands were ascribed to charge-separation in some other sites not related to the oxygen evolving system.

Chloroplasts↗
PubMed1975

[Bronchoplasty].

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Adolescent↗
PubMed1975

Difference-derivative absorbance spectrophotometry as a technique to measure state changes of phenylalanine residues in proteins.

The first derivatives of difference absorbance spectra of several proteins were measured to examine the applicability of this technique as a tool to investigate state changes of phenylalanine residues in proteins. It was found by this technique that phenylalanine residues in insulin and those in lysozyme are exposed to more aqueous environment by denaturation with guanidine hydrochloride. Heat denaturation of collagen caused similar changes of some of its phenylalanine residues. It was thus demonstrated that difference-derivative absorbance spectrophotometry gives the information about state changes of phenylalanine residues in native proteins, which are hardly detected by common difference spectrophotometry.

Air Sacs↗