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1.
Variation and genetic control of seed protein in foxtail millet (Setaria italica) were studied using SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Variation in the electrophoregram of the total seed protein were detected in the range between 20 and 30 kDa which is derived from the polymorphism of five prolamin bands. The segregation for each of the bands in F2 seeds showed that these bands are governed by seven alleles at two loci, Pro1 and Pro2, which are not linked to one another. Among 271 local cultivars examined, eight out of ten possible genotypes were observed. With its level of diversity comparable to that of isozymes, the alleles conferring prolamin polymorphism are useful genetic markers. 相似文献
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Bac Alain Rivoal Katell Cung Manh Thong Boussard Guy Marraud Michel Soudan Benoît Tetaert Daniel Degand Pierre 《International journal of peptide research and therapeutics》1997,4(4-6):251-258
Summary Consequences inherent to the substitution of aza-proline (AzPro) for proline in the octapeptide TTSAPTTS, representative of
the tandem repeat motif present in the peptide backbone of MUC5AC mucin, were analysed in terms of conformational perturbation
and O-glycosylation aptitude. In DMSO solution, we observed the same tendency previously noted in AzPro-tripeptide models,
i.e. AzPro prevents β-turn formation in which it would occupy the i+1 position, and therefore behaves quite opposite to Pro,
whereas both AzPro and Pro can support a β-turn in the i+2 position with a cis disposition of the preceding tertiary amide
function. The former structural modifications do not prevent O-glycosylation to take place at the same specific site, but
it occurs at a reduced rate. 相似文献
3.
The cathelicidin-derived antimicrobial tritrpticin could be classified as either Trp-rich or Pro/Arg-rich peptide. We recently found that the sequence modification of tritrpticin focused on Trp and Pro residues led to considerable change in structure and antimicrobial potency and selectivity, but their mechanisms of microbial killing action were still unclear. Here, to better understand the bactericidal mechanisms of tritrpticin and its two analogs, TPA and TWF, we studied their effect on the viability of Gram-positive S. aureus and Gram-negative E. coli in relation to their membrane depolarization. Although TWF more effectively inhibited growth of S. aureus and E. coli than TPA, only a 30 min exposure to TPA was sufficient to kill both bacteria and TWF required a lag period of about 3-6 h for bactericidal activity. Their different bactericidal kinetics was associated with membrane permeabilization, i.e., TWF showed negligible ability to depolarize the cytoplasmic membrane potential of target cell membrane, whereas we observed significant membrane depolarization for TPA. In addition, while TPA caused rapid and large dye leakage from negatively charged model vesicles, TWF showed very little membrane-disrupting activity. Interestingly, we have looked for a synergism among the three peptides against E. coli, supporting that they are working with different modes of action. Collectively, our results suggest that TPA disrupts the ion gradients across the membrane, causing depolarization and a loss of microbial viability. By contrast, TWF more likely translocates across the cytoplasmic membrane without depolarization and then acts against one or more intracellular targets. Tritrpticin exhibits intermediate properties and appears to act via membrane depolarization coupled to secondary intracellular targeting. 相似文献
4.
Alain Bac Katell Rivoal Manh Thong Cung Guy Boussard Michel Marraud Benoît Soudan Daniel Tetaert Pierre Degand 《Letters in Peptide Science》1997,4(4-6):251-258
Consequences inherent to the substitution ofaza-proline (AzPro) for proline in the octapeptideTTSAPTTS, representative of the tandem repeat motifpresent in the peptide backbone of MUC5AC mucin, wereanalysed in terms of conformational perturbation andO-glycosylation aptitude. In DMSO solution, weobserved the same tendency previously noted inAzPro-tripeptide models, i.e. AzPro prevents-turn formation in which it would occupy thei+1 position, and therefore behaves quite oppositeto Pro, whereas both AzPro and Pro can support a-turn in the i+2 position with a cisdisposition of the preceding tertiary amide function.The former structural modifications do not preventO-glycosylation to take place at the same specificsite, but it occurs at a reduced rate. 相似文献
5.
The cathelicidin-derived antimicrobial tritrpticin could be classified as either Trp-rich or Pro/Arg-rich peptide. We recently found that the sequence modification of tritrpticin focused on Trp and Pro residues led to considerable change in structure and antimicrobial potency and selectivity, but their mechanisms of microbial killing action were still unclear. Here, to better understand the bactericidal mechanisms of tritrpticin and its two analogs, TPA and TWF, we studied their effect on the viability of Gram-positive S. aureus and Gram-negative E. coli in relation to their membrane depolarization. Although TWF more effectively inhibited growth of S. aureus and E. coli than TPA, only a 30 min exposure to TPA was sufficient to kill both bacteria and TWF required a lag period of about 3-6 h for bactericidal activity. Their different bactericidal kinetics was associated with membrane permeabilization, i.e., TWF showed negligible ability to depolarize the cytoplasmic membrane potential of target cell membrane, whereas we observed significant membrane depolarization for TPA. In addition, while TPA caused rapid and large dye leakage from negatively charged model vesicles, TWF showed very little membrane-disrupting activity. Interestingly, we have looked for a synergism among the three peptides against E. coli, supporting that they are working with different modes of action. Collectively, our results suggest that TPA disrupts the ion gradients across the membrane, causing depolarization and a loss of microbial viability. By contrast, TWF more likely translocates across the cytoplasmic membrane without depolarization and then acts against one or more intracellular targets. Tritrpticin exhibits intermediate properties and appears to act via membrane depolarization coupled to secondary intracellular targeting. 相似文献
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W H Melanowski 《Polski tygodnik lekarski (Warsaw, Poland : 1960)》1966,21(39):1507-1508
8.
The structural roles of conserved Pro196, Pro197 and His199 in the mechanism of thymidylate synthase
Gonzalez-Pacanowska D Ruiz-Perez LM Carreras-Gómez MA Costi MP Stroud RM Finer-Moore J Santi DV 《Protein engineering》2003,16(8):607-614
We generated replacement sets for three highly conserved residues, Pro196, Pro197 and His199, that flank the catalytic nucleophile, Cys198. Pro196 and Pro197 have restricted mobility that could be important for the structural transitions known to be essential for activity. To test this hypothesis we obtained and characterized 13 amino acid substitutions for Pro196, 14 for Pro197 and 14 for His199. All of the Pro196 and Pro197 variants, except P197R, and four of the His199 variants complemented TS-deficient Escherichia coli cells, indicating they had at least 1% of wild-type activity. For all His199 mutations, k(cat)/K(m) for substrate and cofactor decreased more than 40-fold, suggesting that the conserved hydrogen bond network co-ordinated by His199 is important for catalysis. Pro196 can be substituted with small hydrophilic residues with little loss in k(cat), but 15- to 23-fold increases in K(m)(dUMP). Small hydrophobic substitutions for Pro197 were most active, and the most conservative mutant, P197A, had only a 5-fold lower k(cat)/K(m)(dUMP) than wild-type TS. Several Pro196 and Pro197 variants were temperature sensitive. The small effects of Pro196 or Pro197 mutations on enzyme kinetics suggest that the conformational restrictions encoded by the Pro-Pro sequence are largely maintained when either member of the pair is mutated. 相似文献
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Allelic variation at the two prolamin loci (Pro1 and Pro2) and its geographical distribution in 560 local cultivars of foxtail millet (Setaria italica) mainly from Eurasia were studied using SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Genetic analysis of a newly detected polymorphic band, band 6, indicated that it is controlled by an allele at the Pro2 locus, which was designated as Pro2f. Two alleles (Pro1a and Pro1null) at the Pro1 locus and six alleles (Pro2a, Pro2b, Pro2c, Pro2d, Pro2e and Pro2f) at the Pro2 locus were detected among the cultivars examined. Although the frequency of the Pro1a allele varied from 0% in the Nansei islands of Japan and Africa to 66% in Afghanistan, no apparent trend was observed in geographical distribution. In contrast, two common alleles at the Pro2 locus, Pro2b and Pro2f, had clear differential geographical distribution. The Pro2b allele was most frequent in Europe and decreased in frequency eastwards. The Pro2f allele occurred frequently in subtropical and tropical regions including the Nansei islands of Japan, the Philippines, Nepal, India, Pakistan and Africa. All eight alleles at the Pro1 and Pro2 loci occurred in China, suggesting China is a center of diversity. The origin of geographical differentiation of local cultivars into a "tropical group" characterized by the Pro2f allele and other genes was discussed. 相似文献
11.
Howard W. Davidson 《Cell biochemistry and biophysics》2004,40(3):143-157
Insulin, the major secreted product of the β-cells of the islets of Langerhans, is initially synthesized as a precursor (preproinsulin), from which the mature hormone is excised by a series of proteolytic cleavages. This review provides a personal narrative of some of the key research projects leading to the identification of the central processing enzymes as proprotein convertase 1, proprotein convertase 2, and carboxypeptidase E. It also discusses the central roles of the intragranular environment and chaperone-like proteins in modulating processing activity. 相似文献
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Turnip yellow mosaic virus (TYMV) is a spherical plant virus that has a single 6.3 kb positive strand RNA. The genomic RNA
has a tRNA-like structure (TLS) at the 3′-end. The 3′-TLS and hairpins in the 5′-untranslated region supposedly serve as packaging
signals; however, recent studies have shown that they do not play a role in TYMV RNA packaging. In this study, we focused
on packaging signals by examining a series of deletion mutants of TYMV. Analysis of encapsidated viral RNA after agroinfiltration
of the deletion constructs into Nicotiana benthamiana showed that the mutant RNA lacking the protease (Pro)/helicase (Hel) region was not encapsidated by the coat proteins provided
in trans, implicating that a packaging signal lies in the Pro/Hel region. Examination of two Pro−Hel− mutants showed that protein activity from the Pro/Hel domains was dispensable for the packaging of the non-replicating TYMV
RNA. In contrast, the mutant TYMV RNA lacking the Pro/Hel region was efficiently encapsidated when the mutant TYMV was co-introduced
with a wild-type TYMV, suggesting that packaging mechanisms might differ depending on whether the virus is replicating or
not. 相似文献
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A meta-analysis was conducted to assess the effect of glutathione peroxidase1 (GPX1) gene Pro200Leu (rs1050450) polymorphism on cancer risk. A comprehensive search was performed to identify all studies on the association of GPX1 gene Pro200Leu polymorphism with cancer risk. The fixed or random effect pooled measure was selected based on homogeneity test among studies. Heterogeneity among studies was evaluated using the I 2. Potential sources of between-study heterogeneity were explored by meta-regression and the sensitivity analysis. Publication bias was estimated using Egger’s linear regression test. 35 published articles with 36 results were identified involving 16,920 cases and 19,946 controls. Results from the articles that both obeyed Hardy–Weinberg equilibrium in controls and met high quality design, showed no significant association of GPX1 gene Pro200Leu polymorphism with cancer risk in any of dominant (OR = 1.05, 95 %CI = 0.98–1.12), recessive (OR = 1.04 (0.95–1.13), and TT versus CC (OR = 1.05, 95 %CI = 0.97–1.15) models, and the findings were consistent considering the stratified analysis by cancer type. However, multivariate-adjusted ORs from articles that both obeyed Hardy–Weinberg equilibrium in controls and met high quality design, showed a significant association considering dominant (OR = 1.22, 95 %CI = 1.06–1.41), TT versus CC (OR = 1.16, 95 %CI = 1.02–1.32) models, and a marginally significant association was found considering TC versus CC (OR = 1.11, 95 %CI = 0.99–1.25) model. And compared with the CC genotype, the erythrocyte GPX activity was significantly lower for TT genotype: the standardized mean difference (SMD) = ?0.37, 95 %CI = (?0.624, ?0.118), and CT genotype: SMD = ?0.19, 95 %CI = (?0.37, ?0.002). The association of GPX1 gene Pro200Leu polymorphism with cancer risk might be influenced by confounders. 相似文献
18.
Ichiro Tomida Hiroshi Kayahara Ryozo Iriye 《Bioscience, biotechnology, and biochemistry》2013,77(11):2549-2555
The degree of racemization in the several activated ester methods of the peptide synthesis was measured in using the critical racemization test, Pro-Val+Pro, with help of gas chromatography. The results were compared with that in the coupling reaction, Leu-Phe+Val, in which no racemization had been reported in the corresponding reaction conditions by F. Weygand et al., when the activated dipeptide esters had been prepared from Z-Leu+Phe-activated esters. The significantly higher racemization was observed in the methods of N-hydroxypiperidine ester and thiophenyl ester, even when the activated dipeptide esters were prepared from Z-Pro+Val-activated esters. On the other hand, almost no racemization was observed in the N-hydroxysuccinimide ester and p-nitrophenyl ester methods. A great extent of the racemization was detected when the activated dipeptide esters were prepared directly from Z-Pro-Val-OH. 相似文献
19.
Seema Jagota Jayakumar Rajadas 《International journal of peptide research and therapeutics》2012,18(1):53-61
Genetic, biochemical and pathological evidence support that self-assembly of amyloid-beta (Aβ) peptide into toxic aggregates
is implicated as the cause of Alzheimer’s disease. An attractive therapeutic strategy for the treatment of AD is to prevent
or interfere with Aβ aggregation. A systematic investigation of the effects of proline-, glycine-, arginine- and lysine- containing
peptides (PGKLVYA, KKLVFFARRRRA and KKLVFFA) on the beta-amyloid aggregation was made using FTIR, circular dichroism, ANS
binding, ThT binding and TEM analysis. These peptides are based on the central hydrophobic region of Aβ (residues 16–20),
which is believed to be crucial in Aβ self-association. There is increasing evidence to suggest that protein aggregation,
including amyloid fibril formation results from the strong self-association tendency of the partially folded intermediates.
Addition of PGKLVYA and KKLVFFARRRRA resulted in increase in ANS fluorescence intensity, suggesting enhanced exposure of hydrophobic
surface area. As observed by ThT and TEM analysis PGKLVYA and KKLVFFARRRRA promote non-fibrillar ensembles, while peptide
KKLVFFA accelerated the fibrillization of Aβ peptide by stabilizing intermolecular interactions. Circular dichroism and FTIR
data showed that PGKLVYA and KKLVFFARRRRA effectively prevented amyloid-beta (Aβ) peptide adopting the beta-sheet secondary
structure correlated with fibrillogenesis. This result indicates that PGKLVYA and KKLVFFARRRRA might have triggered another
mechanism of Aβ assembly. 相似文献
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