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101.
It is known that denaturation of D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) in low concentrations of GuHCl, around 0.5 M, at 25 degrees C, leads first to a burst phase drop of activity, followed by slow unfolding with further loss of enzyme activity and aggregation. However, GAPDH at higher concentrations does not increase the aggregation in the slow phase as would be expected but decreases both the inactivation and aggregation of the enzyme instead. It seems that GAPDH at high concentrations protects the enzyme against GuHCl-denaturation. This protection is not a general effect of GuHCl binding by increased protein concentration but specific for GAPDH, as either bovine serum albumin or alpha-lactalbumin does not show any protection at similar concentrations. It is proposed that dissociation of tetrameric GAPDH into dimers in the early phase of denaturation in dilute GuHCl is reversible and further unfolding of the dimer to an aggregation prone species is irreversible and rate-limiting for the unfolding process. High concentrations of the enzyme shift the equilibrium towards the tetramer thus decrease the aggregation of GAPDH in dilute GuHCl. 相似文献
102.
A perturbation of zinc metabolism has been noted in subjects with obesity. Zinc may also participate in the intracellular
signal cascade by affecting cellular calcium influx and a change in the calcium-calmodulin (CaM)-cyclic adenosine monophosphate
(cAMP) pathway. The possible effects of zinc on cellular concentrations of CaM, a major cytosolic calcium-binding protein,
in the adipocytes derived from obese (ob/ob) mice and their lean counterparts were studied. Adipocytes derived from both phenotypes
of mice were treated either with 0.2 mM of zinc sulfate or without any additive for 1 h of incubation; the cellular levels of CaM and cAMP were then determined.
The results showed that the obese mice had lower CaM and cAMP levels in their adipocytes compared to the lean mice. Zinc treatment
reduced CaM and increased cAMP levels in all mice, although this effect was more pronounced in the lean mice. This study indicated
that there was an inverse interaction between CaM and cAMP in their cellular levels in the mouse adipocytes and that might
be affected by exogenous zinc addition. 相似文献
103.
We investigated the possible correlation between the leptin concentration and the Zn/Cu ratio in the plasma of women with
thyroid disorder. Forty women with hypothyroidism (n=20) or hypothyroidism (n=20) and 20 euthyroid controls were recruited. The results showed that the women with thyroid disorder (hypothyroidism or
hyperthyroidism) had higher plasma leptin concentrations than the normal controls (p<0.05). Moreover, the plasma leptin concentration had no correlation with plasma thyroid hormone levels in the separate groups,
nor among all the participants considered together. A strong correlation (p<0.005) between leptin and adiposity was only observed in euthyroid women. Plasma values of Zn and Cu and the Zn/Cu ratio
were not markedly different among women with altered thyroid status. However, a weak correlation (r=0.28, p=0.032) between leptin and the Zn/Cu ratio was found from the pooled data of all participants and retained after adjustment
for adiposity. We suggest that there may exist an interaction between the plasma leptin level and thyroid hormone-induced
abnormality for selected minerals. 相似文献
104.
105.
Gopalsamy A Yang H Ellingboe JW Tsou HR Zhang N Honores E Powell D Miranda M McGinnis JP Rabindran SK 《Bioorganic & medicinal chemistry letters》2005,15(6):1591-1594
A novel series of p21 chemoselective agents containing a pyrazolo[1,5-a]pyrimidin-7-yl phenyl amides were identified by high throughput screening. Optimization of the amide region by parallel synthesis and the iterative design toward understanding structure-activity relationship to improve potency are described. The isopropyl carbamate derivative 34 was identified as a highly chemoselective agent displaying a potency of 51 nM in the p21 deficient cell line. 相似文献
106.
Tumor necrosis factor-alpha-converting enzyme mediates the inducible cleavage of fractalkine 总被引:10,自引:0,他引:10
Fractalkine (FK, CX3CL1) is a novel multidomain protein expressed on the surface of endothelial cells. As a full-length transmembrane protein, FK binds cells expressing CX3CR1, its cognate receptor, with high affinity. Proteolytic cleavage of FK releases a soluble form that is a potent chemoattractant for monocytes, T cells, and natural killer cells. Activation of protein kinase C dramatically increases the rate of this cleavage. Regulation of FK cleavage is critical for maintaining the balance between the immobilized and soluble forms, but the protease responsible has not been identified. Here we report that tumor necrosis factor-alpha-converting enzyme (TACE) is primarily responsible for the inducible cleavage of FK. After transfection into host cells, the proteolytic cleavage of FK was blocked by TACE-specific inhibitors and was not detected in cells genetically altered to remove TACE activity. In contrast, the constitutive cleavage of FK was not mediated by TACE and proceeded normally in TACE-null fibroblasts. We conclude that TACE is primarily responsible for the inducible cleavage of FK. These studies identify a potentially important link between local generation of potent cytokines and control of the balance between the cell adhesion and chemotactic properties of FK. 相似文献
107.
Yung-An?Tsou Yuan-Kai?ChengEmail author Chia-Der?Lin Weng-Cheng?Chang Ming-Hsui?Tsai 《World journal of surgical oncology》2004,2(1):26
Background
Most lymphomas that involve the tonsil are large B cell lymphomas. Large B-cell lymphoma is a high grade malignancy which progresses rapidly. Tonsillar lymphoma usually presents as either a unilaterally enlarged palatine tonsil or as an ulcerative and fungating lesion over the tonsillar area. Small lymphocytic lymphomas (SLL) of the Waldeyer's ring are uncommon. 相似文献108.
Huang SY Chen MY Lin EC Tsou HL Kuo YH Ju CC Lee WC 《Animal reproduction science》2002,70(1-2):99-109
This study aims to elucidate the effects of single nucleotide polymorphisms (SNPs) in the 5'-flanking region of porcine heat shock protein 70.2 gene (HSP70.2) on semen quality in boars. Genomic DNA isolated from 55 boars (41 Duroc, nine Landrace, and five Yorkshire) was subjected to PCR amplification of the 5'-flanking region of HSP70.2. The nucleotide sequences were determined by automated sequencing. Five SNPs (sites 44, 232, 250, 345, and 393) were detected in this region. Semen quality was evaluated in terms of sperm motility, percentage of normal sperm, percentage of sperm with proximal plasma droplet, percentage of abnormal sperm, sperm concentration, semen volume per ejaculate and total sperm number per ejaculate. The effect of the SNPs on semen quality was evaluated based on breed-corrected data within a season. During the cool season, the sperm motility of boars with AA genotype at the 232 site was significantly higher than that of boars with CC genotype (P<0.05). Meanwhile, boars with AC genotype at the 232 site had higher total sperm number per ejaculate than did those with CC genotype. In the hot season, heterozygotes at both the 232 and 250 sites had significantly higher total sperm number of per ejaculate than AA homozygotes (P<0.05). Semen volume of boars with TT and TC genotypes at the 345 site was significantly larger than that of those with CC genotype (P<0.05). Meanwhile, semen quality for boars with TT genotype at the 345 site was significantly higher than that of boars with TC or CC genotype (P<0.05), that is the semen contained higher percentages of normal sperm and lower percentages of abnormal sperm or sperm with proximal plasma droplets. Results herein suggest that the SNPs in the 5'-flanking region of porcine HSP70.2 are associated with semen quality traits in the hot season. 相似文献
109.
Integrin activation is required for VEGF and FGF receptor protein presence on human microvascular endothelial cells 总被引:4,自引:0,他引:4
Endothelial cell proliferation and migration is initiated by growth factors including FGF and VEGF that bind to specific transmembrane receptor tyrosine kinases. Mechanisms that regulate in vivo expression of fibroblast growth factor receptors (FGFR) and vascular endothelial growth factor receptors (VEGFR) are not well understood. Since it is well known that different matrices influence the proliferation and migration of endothelial cells in culture, we hypothesized that changes in the extracellular matrix environment can regulate growth factor receptors on endothelial cells. We cultured human microvascular endothelial cells on different matrices (vitronectin, laminin, fibronectin, fibrin, and collagen IV) and examined for the presence of growth factor receptors (FGFR-1, FGFR-2, VEGFR-1, and VEGFR-2). We show that vitronectin increased the presence of all four growth factor receptors and most notably, VEGFR-1. In contrast, fibrin decreased all four receptors, especially FGFR-1 and FGFR-2. Inhibiting phosphotyrosine signaling abolished immunostaining for all four receptors, regardless of the matrix, but was not dependent on activating the Fyn-Shc pathway. Cells plated on vitronectin in the presence of blocking antibodies to integrins v3 and v5 similarly decreased presence of these growth factor receptors. Our data suggests a possible mechanism of how matrix-integrin interactions regulate endothelial cell responsiveness to growth factors and anchorage-dependent cell growth. 相似文献
110.
Kwang-Yu Chang Shan-Yin Tsai Shang-Hung Chen Hsiao-Hui Tsou Chia-Jui Yen Ko-Jiunn Liu Hsun-Lang Fang Hung-Chang Wu Bin-Fay Chuang Shao-Wen Chou Careen K Tang Shyun-Yeu Liu Pei-Jung Lu Ching-Yu Yen Jang-Yang Chang 《Journal of biomedical science》2013,20(1):43