Enzyme & protein最新文献_第6页

Translational control of eukaryotic gene expression. Role of the guanine nucleotide exchange factor and chain initiation factor-2. 真核基因表达的翻译控制。鸟嘌呤核苷酸交换因子和链起始因子-2的作用。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474972

L P Singh, A R Aroor, A J Wahba

{"title":"Translational control of eukaryotic gene expression. Role of the guanine nucleotide exchange factor and chain initiation factor-2.","authors":"L P Singh, A R Aroor, A J Wahba","doi":"10.1159/000474972","DOIUrl":"https://doi.org/10.1159/000474972","url":null,"abstract":"In mammalian cells, the guanine nucleotide exchange factor (GEF or eIF-2B) is a key regulator of polypeptide chain initiation. The exchange of GDP bound to chain initiation factor 2 (eIF-2) for GTP by GEF is a rate limiting step in protein synthesis. The multisubunit characteristics of GEF suggest that this protein is composed of several distinct structural and functional domains, and is regulated by allosteric means and by phosphorylation. The activity of GEF may be regulated indirectly by the phosphorylation state of the smallest subunit of eIF-2 (alpha-subunit). On the other hand, phosphorylation of the largest subunit of GEF (82-kD subunit) by casein kinase (CK) I or II stimulates GDP/GTP exchange. GEF contains NADPH which is required for structural integrity of the protein. Upon stimulation of cells by insulin and growth factors, allosteric activation of GEF by sugar phosphates and other effector molecules may also play an important role in the regulation of polypeptide chain initiation. In this article, recent information about structure-function relationship of eIF-2 and GEF in nucleotide exchange and the regulatory mechanisms that influence the rate of polypeptide chain initiation under various physiological and pathological conditions are presented.","PeriodicalId":11854,"journal":{"name":"Enzyme & protein","volume":"48 2","pages":"61-80"},"PeriodicalIF":0.0,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000474972","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18587464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Properties of rat liver L-threonine deaminase. 大鼠肝脏l -苏氨酸脱氨酶的性质。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474974

R Pagani, R Leoncini, M Pizzichini, D Vannoni, A Tabucchi, E Marinello

引用次数: 4

Effect of grape seed tannins on the activity of some rat intestinal enzyme activities. 葡萄籽单宁对大鼠肠道酶活性的影响。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474969

K Tebib, J M Rouanet, P Besançon

{"title":"Effect of grape seed tannins on the activity of some rat intestinal enzyme activities.","authors":"K Tebib, J M Rouanet, P Besançon","doi":"10.1159/000474969","DOIUrl":"https://doi.org/10.1159/000474969","url":null,"abstract":"The present study was designed to investigate the effects of grape seed tannins on rat intestinal alkaline phosphatase (AP), sucrase and dipeptidyl peptidase IV (DPP IV) activities. An experiment was performed in vivo by dietary supplementation with 2% tannins; this diet was tested on an experimental group of rats; a control group received a diet without tannins. After 31 days, tannins intake significantly decreased middle-jejunal AP from 123 to 45 mU/mg protein and sucrase activities from 310 to 195 mU/mg protein, while no significant difference appeared at the duodenal stage (p < 0.05). Ileal DPP IV activity was also significantly reduced (p < 0.05) from 190 to 110 mU/mg protein after tannin intake. Using in vitro experiments on purified brush border membranes, AP activity was found to be inhibited by grape tannins; this inhibition was prevented by the detergent Triton X-100. The addition of pancreatic-biliary (PB) juice to the incubation medium prevented or reversed the tannin-inhibited enzyme activity. The present data indicate that in the duodenal lumen, alkalinity and detergency from the PB secretion neutralized the ability of tannins to inactivate brush border hydrolase activities and suggest that enzyme inhibition took place once bile salts were reabsorbed while moving down the gut. This was confirmed by in vitro experiments where sucrase and DPP IV activities inhibited by grape seed tannins were largely recovered after the addition of PB juice to the incubation medium.","PeriodicalId":11854,"journal":{"name":"Enzyme & protein","volume":"48 1","pages":"51-60"},"PeriodicalIF":0.0,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000474969","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18787427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 33

A sensitive enzyme-linked immunosorbent assay of serum ornithine carbamoyltransferase. 血清鸟氨酸氨基甲酰转移酶的灵敏酶联免疫吸附测定。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474964

Y Watanabe, S Mori, M Ozaki, S Fujiyama, T Sato, M Mori

引用次数: 5

Insulin-degrading activity in experimental liver cirrhosis of the rat. 实验性肝硬化大鼠胰岛素降解活性的研究。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474989

M Auletta, S Antoniello, N Abrescia

引用次数: 4

Effect of proximal tubular glucose transport blockade on urinary enzyme excretions in hyperglycemic rats. 近端小管葡萄糖转运阻滞对高血糖大鼠尿酶排泄的影响。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474997

N Ishii, Z Ogawa, H Itoh, H Ikenaga, T Saruta

{"title":"Effect of proximal tubular glucose transport blockade on urinary enzyme excretions in hyperglycemic rats.","authors":"N Ishii, Z Ogawa, H Itoh, H Ikenaga, T Saruta","doi":"10.1159/000474997","DOIUrl":"https://doi.org/10.1159/000474997","url":null,"abstract":"To investigate proximal tubular dysfunction under hyperglycemic status, we infused 10% glucose solution into male Wistar rats with and without 0.16% phloridzin (a specific inhibitor of proximal tubular glucose transportation) and measured the urinary excretion rates of enzymes that are derived predominantly from proximal tubules. We used 10% mannitol solution and 0.9% saline as controls. Urinary excretion levels of N-acetyl-ss-D-glucosaminidase, alanine aminopeptidase, gamma-glutamyl transpeptidase and dipeptidyl aminopeptidase IV were significantly increased in the 10% glucose-loaded group. In contrast, these increased enzyme excretions were not observed in the 10% mannitol or 0.9% saline-loaded group. Moreover, addition of 0.16% phloridzin to 10% glucose solution completely prevented these increases in N-acetyl-beta-D-glucosaminidase, alanine aminopeptidase and gamma-glutamyl transpeptidase excretion, and slightly decreased dipeptidyl aminopeptidase IV excretion. At the end of the infusion study, a rise in renal cortical sorbitol concentration of the 10% glucose-loaded group was about 2 times higher than the 0.9% saline or 10% mannitol-loaded group. However, in the group that received both glucose and phloridzin, elevation of renal cortical sorbitol concentration was not observed. This study showed that glucose-load results in both abnormal enzymuria and renal cortical sorbitol accumulation; they were completely prevented by phloridzin.","PeriodicalId":11854,"journal":{"name":"Enzyme & protein","volume":"48 5-6","pages":"243-50"},"PeriodicalIF":0.0,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000474997","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19763964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Induced expression of alpha-enolase in differentiated diffuse large cell lymphoma. α -烯醇化酶在分化性弥漫性大细胞淋巴瘤中的诱导表达。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474967

R M Mohammad, M Y Hamdan, A al-Katib

引用次数: 10

Spectroscopic studies on angiotensin I-converting enzyme. 血管紧张素i转换酶的光谱研究。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474999

B Baudin, N Mario, S Gaba, J Giboudeau

{"title":"Spectroscopic studies on angiotensin I-converting enzyme.","authors":"B Baudin, N Mario, S Gaba, J Giboudeau","doi":"10.1159/000474999","DOIUrl":"https://doi.org/10.1159/000474999","url":null,"abstract":"We used near and far UV spectrophotometry for the re-evaluation of the molar extinction coefficient at 280 nm (epsilon 280) of pulmonary angiotensin-converting enzyme (ACE), for the determination of its tryptophan and tyrosine contents and to follow-up guanidine denaturation. ACE purity was assessed by both SDS-PAGE and capillary electrophoresis performed in denaturing conditions. The maxima of the near UV spectrum of purified ACE, dissolved in phosphate buffer pH 6.5, was at 279 nm; with an estimated M(r) of 160 kD, epsilon 280 of native ACE was 1.5 +/- 0.05 x 10(5) (mol/l)-1 x cm-1. Denaturation of ACE by 6 mol/l guanidine hydrochloride produced a hypochromic effect of 23% at 280 nm and led to a blue shift of 3.5 nm. In guanidine solution, absorbance measurements at 288 and 280 nm predicted a ratio of 1 between tyrosine and tryptophan, whereas it was 1.8 with the measure of the amplitude of the spectral bands at 283 and 292 nm of the second derivative of the near UV spectrum. Unfolding of the peptide chain in 6 mol/l guanidine was also well characterized by the second derivative of the far UV spectrum, in parallel with the complete loss of enzymatic activity although the protein remained whole as judged on SDS-PAGE. We also re-evaluated ACE zinc content by atomic absorption spectroscopy and demonstrated that ACE molecule obviously contains two zinc atoms.","PeriodicalId":11854,"journal":{"name":"Enzyme & protein","volume":"48 5-6","pages":"265-74"},"PeriodicalIF":0.0,"publicationDate":"1994-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000474999","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19765115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Creatine kinase activity decrease with short-term freezing. 肌酸激酶活性随短期冷冻而降低。

Enzyme & protein Pub Date : 1994-01-01 DOI: 10.1159/000474994

E I Lev, I Hendler, R Siebner, Z Tashma, M Wiener, I Tur-Kaspa

引用次数: 12

Bovine lens multicatalytic proteinase complex. 牛晶状体多催化蛋白酶复合物。

Enzyme & protein Pub Date : 1993-01-01 DOI: 10.1159/000468679

B J Wagner, J W Margolis, I Singh

引用次数: 7