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1.
Purification, N-terminal amino acid sequence and characterization of pH 2.5 optimum acid phosphatase (E.C. 3.1.3.2) from Aspergillus ficuum 总被引:2,自引:0,他引:2
An acid phosphatase from crude culture filtrate of Aspergillus ficuum was purified to homogeneity using three ion exchange chromatographic steps. SDS-PAGE of the purified enzyme gave a single stained band at approximately 68-KDa. The mobility of the native enzyme in gel filtration chromatography, however, indicated that the molecular mass to be about 130-KDa implying the active form to be a dimer. On the basis of a molecular mass of 68-KDa, the molar extinction coefficient of the enzyme at 280 nm was estimated to be 3.4 x 10(5) M-1 cm-1. The isoelectric point of the enzyme, as judged by chromatofocusing, was about 4.0. The purified enzyme is highly stable at 0 degree C. Thermal inactivation studies have indicated that the enzyme is unstable at 70 degrees C. The enzyme, however, exhibited a broad temperature optima with a maximum catalytic activity at 63 degrees C. The Km of the enzyme for p-nitrophenylphosphate is about 270 microM with an estimated turnover number of 2550 per sec. The enzyme is a glycoprotein as evidenced by the positive PAS staining; the sugar composition suggests the presence of N-linked high mannose-oligosaccharides. A partial N-terminal amino acid sequence up to the twenty-third residue was obtained. The enzyme was inhibited competitively by inorganic orthophosphate (Ki = 185 microM) and non-competitively by phosphomycin (Ki = 600 microM). 相似文献
2.
The data presented clearly suggest that relative amounts of mRNAs for elastins a, b and c are developmentally regulated in foetal-calf nuchal ligament and aorta and that this regulation is tissue-specific. In nuchal ligament, at earlier stages of foetal development, the relative amounts of mRNAs for elastins a and b are very low. After the foetal age of about 6 months the relative amount of mRNA for elastin b begins to increase. This is followed by an increase in the relative amount of mRNA for elastin a. In aorta, with increasing foetal age, the relative amounts of mRNAs for elastins b and c increase and decrease alternately. The relative amounts of mRNA for elastin a remain low, with only marginal increases with foetal age. A possible self-aggregation role of elastin a in elastogenesis is proposed. 相似文献
3.
Cytogenetic effects in a group of traffic policemen in Cairo 总被引:3,自引:0,他引:3
The aim of this study was to evaluate the cytogenetic effects in humans exposed to automobile exhaust. The induction of chromosome damage was studied in an exposed group of 28 traffic policemen with exposure of over 10 years and a control group of 15 policemen trainers from the Faculty of Police. The percentage of chromosomal aberrations as well as the mean sister-chromatid exchanges were significantly higher among the traffic policemen than in the control group. The cause for this elevated chromosome damage is most likely due to their exposure to pollutants from automobile exhaust, however, the increase is not correlated with the blood lead level or the duration of employment. On the other hand, the increase in chromosome damage among the traffic policemen is enhanced further by smoking. 相似文献
4.
Aspergillus ficuum phytase: partial primary structure, substrate selectivity, and kinetic characterization 总被引:10,自引:0,他引:10
A H Ullah 《Preparative biochemistry》1988,18(4):459-471
Purified Aspergillus ficuum phytase's partial primary structure and amino acid and sugar composition were elucidated. Determination of kinetic parameters of the enzyme at different pH values and temperatures indicated no significant alteration of the Km for phytate while the Kcat was affected. The enzyme was able to release more than 51% of the total available Pi from phytate in a 3.0 hr assay at 58 degrees C, but the Kcat dropped to 15% of the initial rate. Substrate selectivity studies revealed phytate to be the preferred substrate. The pH optima of phytase was 5.0, 4.0, and 3.0 for phytate, ATP, and polyphosphate, respectively. The enzyme had varied sensitivity towards cations. While Ca++ and Fe++ produced no effect on the catalytic rate of the enzyme, Cu+, Cu++, Zn++, and Fe were found to be inhibitory. Mn++ was observed to enhance enzyme activity by 33% at 50 microM. Known inhibitors of acid phosphatases e.g. L (+)-tartrate, phosphomycin, and sodium fluoride had no effect on enzyme activity. 相似文献
5.
Alia Islam Obaid Ullah Beg Bengt Persson Zafar H. Zaidi Hans Jörnvall 《The protein journal》1988,7(5):561-569
The structure of the hernoglobin α-chain of Rose-ringed Parakeet was determined by sequence degradations of the intact subunit, the CNBr fragments, and peptides obtained by digestion with staphylococcal Glu-specific protease and trypsin. Using this analysis, the complete α-chain structure of 21 avian species is known, permitting comparisons of the protein structure and of avian relationships. The structure exhibits differences from previously established avian α-chains at a total of 61 positions, five of which have residues unique to those of the parakeet (Ser-12, Gly-65, Ser-67, Ala-121, and Leu-134). The analysis defines hemoglobin variation within an additional avian order (Psittaciformes), demonstrates distant patterns for evaluation of relationships within other avian orders, and lends support to taxonomic conclusions from molecular data. 相似文献
6.
Improper timing of artificial insemination with respect to ovulation is one of the major factors hampering the conception rate in buffalo. The present study was an attempt to relate physio-chemical changes in estrual mucus to subsequent pregnancy status in order to find their optimal values for determining the time for artificial insemination (AI). Serum estradiol, total protein and dry matter contents of estrual mucus were evaluated to predict the subsequent pregnancy in 36 buffalo during October 1988 to February 1989. Serum estradiol was determined by radioimmunoassay (RIA); spinnbarkeit, dry matter and total protein were determined by standard methods. Multivariate probit analyses were carried out to relate these variables to subsequent pregnancy status. Elasticity and protein concentration were significantly related to prediction probability of pregnancy status, and they predicted the pregnancy status 86% of the times correctly (P < 0.05). The probability of pregnant animals being correctly classified was 0.76, whereas the corresponding value for non-pregnant animals was 0.95. The present study demonstrated the possibility of using such a statistical model on mucus characteristics for determining proper AI time for better conception rates in Nili-Ravi water buffalo. 相似文献
7.
E. J. Mullaney D. M. Gibson A. H. J. Ullah 《Applied microbiology and biotechnology》1991,35(5):611-614
Summary As the initial step in a project to provide a more cost-effective source of the phytase enzyme, this paper reports on the use of a polyclonal antibody raised to phytase purified from an isolate of Aspergillus niger (A. ficuum) to screen an A. niger lambda gt11 expression library and the use of amino acid sequencing to identify a clone containing part of the fungal phytase gene. The described use of amino acid sequence fragments to verify the cloning of a gene has potential applications in other cloning projects.Mention of a trademark or proprietary product does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply approval to the exclusion of other products that may also be suitable
Offprint requests to: E. Mullaney 相似文献
8.
Outer membrane proteins of gentamicin induced small colony variants of Pseudomonas aeruginosa 总被引:1,自引:0,他引:1
Small colony variants (SCVs) of Pseudomonas aeruginosa NCTC 6750 (WT) were repeatedly isolated in an in vitro kinetic model after exposure to gentamicin (GM). There were minor differences biochemically and in phage and serotyping between the wild type (WT) strain and SCVs. Changes in outer membrane protein profiles were found. SCVs were more resistant to polymixin and to a range of aminoglycosides (except kanamycin), but were more susceptible to a range of other antibiotics (hydrophilic and hydrophobic) with differing modes of action. 相似文献
9.
Ahsan Ullah Khan 《Luminescence》1995,10(6):329-333
Simple acidification of aqueous alkaline peroxynitrite quantitatively generates singlet (1Δg) molecular oxygen, detected and quantitated spectroscopically (1270 nm). This observation provides a chemical basis for physiological cytotoxicity of ONOO? generated in the diffusion - controlled reaction of cellular NO? and O. The experiments consist of (i) chemical generation of ONOO? from NO? gas and KO2 powder in alkaline aqueous solution; (ii) absorption spectral identification of ONOO? in the near-UV with maximum at 302 nm; (iii) spectroscopic identification of 1O2 by its emission band at 1200–1340 nm with maximum at 1275 nm; and (iv) quantitation of 1O2 generated in ONOO?/H+ reaction by comparison of the chemiluminescence intensity at 1270 nm with that from H2O2/OCl? reaction that generates 1O2 with unit efficiency at alkaline pH. 1O2 was generated with unit efficiency with respect to ONOO? concentration by the ONOO?/H+ reaction. 相似文献
10.
Seeds of seven dune species were collected from sand dunes of Lakes Erie and Huron and buried to various depths in a natural sand dune habitat along Lake Huron. The seed samples were then retrieved after varying lengths of time and examined for their germinability and dormancy. Results showed that buried seeds remained viable for at least 2.5 years and had the potential to form a persistent seed bank. Seed banks were larger and longer lasting at greater depths of burial than those at shallow burial depths. The results suggested that failure to verify the existence of effective seed banks in previous studies may be due to insufficient number of samples, shallow sample depth, local population variations, and fruiting events. Several species also possessed a temporary, aboveground seed reserve formed by retention of a small proportion of viable seeds on the previous year's inflorescences. In some species, seeds retained aboveground were dormant and thus capable of forming a persistent seed bank when they entered the soil. 相似文献