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31.
32.
The absolute activities of ADPG(UDPG)-pyrophosphorylase, starch phosphorylase, ADPG(UDPG)-starch synthetase, NDP-kinase and inorganic pyrophosphatase have been studied in high lysine mutant barley Notch-2 and its parent NP 113 grains during development. In general, mutant Notch-2 grains had higher average activities of UDPG-pyrophosphorylase and starch phosphorylase and lower activity of ADPG(UDPG)-starch synthetase per grain than the parent NP 113 during grain development. Activities of NDP-kinase, ADPG-pyrophosphorylase and inorganic pyrophosphatase differed only to a small extent between the mutant Notch-2 and NP 113. It is suggested that the lower activity of ADPG(UDPG)-starch synthetase might be responsible for the reduced accumulation of starch in the mutant Notch-2 grain as compared with parent NP 113 during development. 相似文献
33.
Magdolna Varsányi Andreja Vrbica Ludwig M. G. Heilmeyer Jr. 《Biochemical genetics》1980,18(3-4):247-261
A new mouse strain, the V strain, with a partial deficiency of phosphorylase kinase has been established. The deficiency is caused by an X-linked dominant gene (Phk
c
). Muscle extracts of homozygous and heterozygous females and hemizygous males have about 25% of the activity found in extracts of normal (C3H/HeHan) mice. This dominant phosphorylase kinase deficiency of the new V strain is different from that of the I-strain mice with the X-linked recessive deficiency of skeletal muscle phosphorylase kinase. The muscle extracts of V-strain and normal mice contain the same phosphorylase phosphatase activity of about 1 U/mg. Heart and liver extracts from V mice contained about 50% and 66%, respectively, of the phosphorylase kinase activity compared to that found in the same organs from the normal mice. The glycogen content of the skeletal muscle of the V strain was normal, i.e., 0.9 mg/g. Phosphorylase kinase was purified from the skeletal muscle of the V strain by (a) hydrophobic chromatography on methylamine Sepharose, (b) ammonium sulfate precipitation, and (c) gel filtration of Sepharose 4B. The enzyme has a similar structure to the normal murine and rabbit skeletal muscle enzyme, except that the proportion of the subunits differs. The molar ratio of the subunits of the V strain mice is (+)::=0.54:1:1.169, in comparison with that of the rabbit (+)::=1.1:1.0:1.0 and that of normal murine enzyme 0.9:1.0:0.7.This work was supported by the Minister für Wissenschaft und Forschung des Landes Nordrhein-Westfalen, West Germany and of the Fonds der Chemie, West Germany, and forms part of the md thesis of A. Vrbica. 相似文献
34.
Genetic evidence for a trimeric structure for purine nucleoside phosphorylase in the brook lamprey is presented. This enzyme is encoded by a single locus with two alleles segregating at frequencies of 0.98 and 0.02 in a Welsh population. It is suggested that this enzyme is likely to be a trimer in all classes of vertebrates.B. J. McAndrew and G. P. Wallis were supported by NERC Research Studentships. 相似文献
35.
Summary The cumulus and membrana granulosa of non-atretic ovarian follicles from primordial up to a stage shortly before ovulation were studied by electron microscopy.The follicular cells of primordial follicles were undifferentiated and rested on a thick basal lamina. In secondary follicles the endoplasmic reticulum had proliferated forming an anastomosing network. In early antral and antral follicles (0.5–2.0 mm dia.) the ER was composed of short cisternae, the mitochondria had elongated and gap junctions were first observed. In late antral follicles (3.0–5.9 mm dia.) gap junctions were frequent. In the cumulus the glycogen was associated with electron lucent areas whereas in the granulosa it was invariably associated with membranes. In large antral follicles large membrane bound bodies were present in the basal cells of the cumulus. At early oestrus a distinctive mitochondrial morphology was noted in the granulosa but not elsewhere in the follicles. At mid oestrus numerous annular nexuses were present in the granulosa but not in the cumulus. At late oestrus numerous lipid droplets were formed in both cumulus and granulosa, the boundary with theca interna became indistinct and the basal lamina became incomplete.Deceased 相似文献
36.
Summary The regulation of the synthesis of nucleoside metabolizing enzymes has been studied in cya and crp mutant strains of Escherichia coli.The synthesis of the cyt-enzymes, cytidine deaminase and uridine phosphorylase regulated by the cytR gene product, is activated by the cAMP-CRP complex. On the other hand the synthesis of the deoenzymes: deoxyriboaldolase, thymidine phosphorylase, phosphodeoxyribomutase and purine nucleoside phosphorylase, appears to be increased if an active cAMP-CRP complex cannot be formed.It also seems that nucleosides serve as poor carbon sources for cya and crp mutants; this could not solely be explained by low levels of nucleoside metabolizing enzymes nor by a deficiency in nucleoside uptake. Addition of casamino acids stimulated the growth of cya and crp mutants, with nucleosides as carbon sources. When grown on glucose and casamino acids growth could be stimulated by adenine and hypoxanthine nucleosides; these results suggest an impaired nitrogen metabolism in cya and crp mutants.Abbreviations and Symbols cAMP
cyclic adenosine 3:5-monophosphate
- CRP
cAMP receptor protein. Genes coding for: adenyl cyclase
-
cya
cAMP receptor protein
-
crp
cytidine deaminase
-
cdd
uridine phosphorylase
-
udp
thymidine phosphorylase
-
tpp
purine nucleoside phosphorylase
-
pup; cytR
regulatory gene for cdd, udp, dra, tpp, drm, and pup
-
deoR
regulatory gene for dra, tpp, drm, and pup 相似文献
37.
38.
Changes in the activity of phosphorylase were measured during storage of potatoes at + 2° when the sugar content rises rapidly and subsequently at + 10° when the accumulated sugar is converted mainly to starch. The observed changes were relatively small and could not be related to any of the components of the phosphorylase system, which was shown to be complex. 相似文献
39.
C. C. WANG R. M. WEPPELMAN B. LOPEZ-RAMOS 《The Journal of eukaryotic microbiology》1975,22(4):560-564
SYNOPSIS. Amylopectin granules were purified from Eimeria tenella oocysts following digestion with sodium dodecyl sulfate and pronase. The oval granules had a uniform size of 0.5 × 0.7 μm, and consisted of only glucose polymers. α-Amylase treatment yielded 235 nmoles of maltose from the granules from 106 unsporulated oocysts and 93 nmoles maltose from those from 106 sporulated oocysts.
Amylopectin phosphorylase activity was detected in the cytoplasm of unsporulated oocysts of E. tenella. It had a specific activity of 13 U/mg protein in crude extracts, and a pH optimum of 6.0. The K m values determined were 9.1 mM for glucose-1-phosphate and 5.6 mM for glucose end groups in potato amylopectin. Enzyme activity declined at a linear rate during sporulation, sporulated oocysts containing less than 8% of the activity of unsporulated oocysts. No amylase-type activity was found in the parasite. 相似文献
Amylopectin phosphorylase activity was detected in the cytoplasm of unsporulated oocysts of E. tenella. It had a specific activity of 13 U/mg protein in crude extracts, and a pH optimum of 6.0. The K m values determined were 9.1 mM for glucose-1-phosphate and 5.6 mM for glucose end groups in potato amylopectin. Enzyme activity declined at a linear rate during sporulation, sporulated oocysts containing less than 8% of the activity of unsporulated oocysts. No amylase-type activity was found in the parasite. 相似文献
40.
Gye Sun Jeon Jee-Eun Kim Suk-Won Ahn Kyung-Seok Park Yoon-Ho Hong In-Hae Ye Ji-Seon Park Seung Hyun Kim Kwang-Woo Lee Sung-Min Kim Jung-Joon Sung 《Biochemical and biophysical research communications》2013
Glycogen synthase kinase-3β (GSK-3β) has been identified as one of the important pathogenic mechanisms in motor neuronal death. GSK-3β inhibitor has been investigated as a modulator of apoptosis and has been shown to confer significant protective effects on cell death in neurodegenerative diseases. However, GSK-3β is known to have paradoxical effects on apoptosis subtypes, i.e., pro-apoptotic in mitochondrial-associated intrinsic apoptosis, but anti-apoptotic in death receptor-related extrinsic apoptosis. In this study, we evaluated the effect of a new GSK-3β inhibitor (JGK-263) on motor neuron cell survival and apoptosis, by using low to high doses of JGK-263 after 48 h of serum withdrawal, and monitoring changes in extrinsic apoptosis pathway components, including Fas, FasL, cleaved caspase-8, p38α, and the Fas–Daxx interaction. Cell survival peaked after treatment of serum-deprived cells with 50 μM JGK-263. The present study showed that treatment with JGK-263 reduced serum-deprivation-induced motor neuronal apoptosis by inactivating not only the intrinsic, but also the extrinsic apoptosis pathway. These results suggest that JGK-263 has a neuroprotective effect through effective modulation of the extrinsic apoptosis pathway in motor neuron degeneration. 相似文献