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41.
Crystal structure of an anti-interleukin-2 monoclonal antibody Fab complexed with an antigenic nonapeptide 下载免费PDF全文
Afonin PV Fokin AV Tsygannik IN Mikhailova IY Onoprienko LV Mikhaleva II Ivanov VT Mareeva TY Nesmeyanov VA Li N Pangborn WA Duax WL Pletnev VZ 《Protein science : a publication of the Protein Society》2001,10(8):1514-1521
The three-dimensional structure of the Fab fragment of a monoclonal antibody (LNKB-2) to human interleukin-2 (IL-2) complexed with a synthetic antigenic nonapeptide, Ac-Lys-Pro-Leu-Glu-Glu-Val-Leu-Asn-Leu-OMe, has been determined at 3.0 A resolution. In the structure, four out of the six hypervariable loops of the Fab (complementarity determining regions [CDRs] L1, H1, H2, and H3) are involved in peptide association through hydrogen bonding, salt bridge formation, and hydrophobic interactions. The Tyr residues in the Fab antigen binding site play a major role in antigen-antibody recognition. The structures of the complexed and uncomplexed Fab were compared. In the antigen binding site the CDR-L1 loop of the antibody shows the largest structural changes upon peptide binding. The peptide adopts a mostly alpha-helical conformation similar to that in the epitope fragment 64-72 of the IL-2 antigen. The side chains of residues Leu 66, Val 69, and Leu 70, which are shielded internally in the IL-2 structure, are involved in interactions with the Fab in the complex studied. This indicates that antibody-antigen complexation involves a significant rearrangement of the epitope-containing region of the IL-2 with retention of the alpha-helical character of the epitope fragment. 相似文献
42.
Makarov VV Dzhupina SI Vedernikov VA Zavodskikh AV Afonin VN 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2002,(5):21-25
During the 23 year period rabies was registered in the Moscow region in 163 cases among foxes, 22 cases among racoon-like dogs, 92 cases among dogs, 54 cases among cats. In 1991-2000 ten cases of rabies were registered among other wild animal other than foxes and raccoon-like dogs (hares, hedge-hogs, polecats, badgers, hamsters, martens, rats). Under today conditions the generalized epizootological pattern of rabies is characterized by the vector "natural foci-->anthropurgic foci" with wild and domestic animals playing an alternative role in the epizootic process and the circulation of the infective agent. Wild carnivorous animals maintain natural focal infection in time and space, while all domestic animals are a direct or indirect ecological impasse and took no part in the maintenance of the infection. Foxes are the main source of infection for the animals of the anthropurgic cycle: they play a special role in the development of the epizootic situation in the region as the main reservoir and source of the causative agent of rabies as a natural focal infection. Among other wild animals, raccoon-like dogs are involved into epizootic and epidemic chains. Dogs are the main objects to be infected in the anthropurgic cycles, while cats--a progressing group of risk. During the period of 25 years a decrease in the probability of natural rabies was noted. 相似文献
43.
Zorbas YG Yarullin VL Denogradov SD Afonin VB Kakurin VJ 《Biological trace element research》2000,73(3):211-229
Electrolyte metabolism undergoes significant changes in trained subjects, but it is unknown if it undergoes significant changes
in untrained subjects during hypokinesia (decreased movement). The aim of this study was to measure calcium (Ca) changes in
trained and untrained subjects during prolonged hypokinesia (HK).
Studies were done during 30 d of a pre-HK period and 364 d of a HK period. Forty male trained and untrained volunteers aged
23–26 yr were chosen as subjects. All subjects were equally divided into four groups: trained ambulatory control subjects
(TACS), trained hypokinetic subjects (THKS), untrained hypokinetic subjects (UHKS), and untrained ambulatory control subjects
(UACS). The THKS and UHKS groups were kept under an average running distance of 0.7 km/d.
Fecal Ca excretion, urinary Ca and magnesium (Mg) excretion, serum ionized calcium (CaI), Ca, Mg, intact parathyroid hormone (iPTH) and 1,25 dihydroxyvitamin D [1,25 (OH)2 D] concentration, body weight, and peak
oxygen uptake were measured. Fecal Ca loss, urinary Ca and Mg excretion, and serum CaI, Mg, and Ca increased significantly (p ≤ 0.01), whereas serum iPTH and 1,25 (OH)2 D concentration body weight and peak oxygen uptake decreased significantly (p ≤ 0.01) in the THKS and UHKS groups when compared with the TACS and UACS groups. The measured parameters were much greater
and much faster in the THKS group than in the UHKS group. By contrast, the corresponding parameters did not change significantly
in the TACS and UACS groups when compared with the baseline control values.
It was concluded that prolonged HK induces significant fecal, urinary, and serum Ca changes in the hypokinetic subjects when
compared with control subjects. However, fecal, urinary, and serum Ca changes were much greater and appeared much faster in
the THKS group than the UHKS group. 相似文献
44.
The Ability of Aneurinibacillus migulanus (Bacillus brevis) To Produce the Antibiotic Gramicidin S Is Correlated with Phenotype Variation 下载免费PDF全文
Phenotype instability of bacterial strains can cause significant problems in biotechnological applications, since industrially useful properties may be lost. Here we report such degenerative dissociation for Aneurinibacillus migulanus (formerly known as Bacillus brevis) an established producer of the antimicrobial peptide gramicidin S (GS). Phenotypic variations within and between various strains maintained in different culture collections are demonstrated. The type strain, ATCC 9999, consists of six colony morphology variants, R, RC, RP, RT, SC, and SP, which were isolated and characterized as pure cultures. Correlations between colony morphology, growth, GS production, spore formation, and resistance to their own antimicrobial peptide were established in this study. We found the original R form to be the best producer, followed by RC, RP, and RT, while SC and SP yielded no GS at all. Currently available ATCC 9999T contains only 2% of the original R producer and is dominated by the newly described phenotypes RC and RP. No original R form is detected in the nominally equivalent strain DSM 2895T (=ATCC 9999T), which grows only as SC and SP phenotypes and has thus completely lost its value as a peptide producer. Two other strains from the same collection, DSM 5668 and DSM 5759, contain the unproductive SC variant and the GS-producing RC form, respectively. We describe the growth and maintenance conditions that stabilize certain colony phenotypes and reduce the degree of degenerative dissociation, thus providing a recommendation for how to revert the nonproducing smooth phenotypes to the valuable GS-producing rough ones. 相似文献
45.
46.
Phenotype instability of bacterial strains can cause significant problems in biotechnological applications, since industrially useful properties may be lost. Here we report such degenerative dissociation for Aneurinibacillus migulanus (formerly known as Bacillus brevis) an established producer of the antimicrobial peptide gramicidin S (GS). Phenotypic variations within and between various strains maintained in different culture collections are demonstrated. The type strain, ATCC 9999, consists of six colony morphology variants, R, RC, RP, RT, SC, and SP, which were isolated and characterized as pure cultures. Correlations between colony morphology, growth, GS production, spore formation, and resistance to their own antimicrobial peptide were established in this study. We found the original R form to be the best producer, followed by RC, RP, and RT, while SC and SP yielded no GS at all. Currently available ATCC 9999(T) contains only 2% of the original R producer and is dominated by the newly described phenotypes RC and RP. No original R form is detected in the nominally equivalent strain DSM 2895(T) (=ATCC 9999(T)), which grows only as SC and SP phenotypes and has thus completely lost its value as a peptide producer. Two other strains from the same collection, DSM 5668 and DSM 5759, contain the unproductive SC variant and the GS-producing RC form, respectively. We describe the growth and maintenance conditions that stabilize certain colony phenotypes and reduce the degree of degenerative dissociation, thus providing a recommendation for how to revert the nonproducing smooth phenotypes to the valuable GS-producing rough ones. 相似文献
47.
Yan G. Zorbas Vassil J. Kakurin Victor B. Afonin Nikolai A. Kuznetsov Vladimir L. Yarullin Sergei D. Denogradov 《Biological trace element research》1999,70(1):1-19
Negative potassium balance during hypokinesia (decreased number of kilometers taken/day) is not based on the potassium shortage
in the diet, but on the impossibility of the body to retain potassium. To assess this hypothesis, we study the effect of potassium
loading on athletes during prolonged hypokinesia (HK).
Studies were done during 30 d of a pre-HK period and during 364 d of an HK period. Forty male athletes aged 23–26 yr were
chosen as subjects. They were divided equally into four groups: unloaded ambulatory control subjects (UACS), unloaded hypokinetic
subjects (UHKS), loaded hypokinetic subjects (LHKS), and loaded ambulatory control subjects (LACS). For the simulation of
the hypokinetic effect, the LHKS and UHKS groups were kept under an average running distance of 1.7 km/d. In the LACS and
LHKS groups, potassium loading tests were done by administering 95.35 mg KC1 per kg body weight.
During the pre-HK and HK periods and after KC1 loading tests, fecal and urinary potassium excretion, sodium and chloride excretion,
plasma potassium, sodium and chloride concentration, and potassium balance were measured. Plasma renin activity (PRA) and
plasma aldosterone concentration was also measured. Negative potassium balance increased significantly (p < -0.01) in the UHKS and LHKS groups when compared with the UACS and LACS groups. Plasma electrolyte concentration, urinary
electrolyte excretion, fecal potassium excretion, PRA, and PA concentration increased significantly (p ≤ 0.01) in the LHKS
and UHKS groups when compared with LACS and UACS groups. Urinary and fecal potassium excretion increased much more and much
faster in the LHKS group than in the UHKS group. By contrast, the corresponding parameters change insignificantly in the UACS
and LACS groups when compared with the base line control values.
It was concluded that urinary and fecal potassium excretion increased significantly despite the presence of negative potassium
balance; thus, negative potassium balance may not be based on potassium shortage in the diet because of the impossibility
of the body to retain potassium during HK. 相似文献
48.
V. I. Afonin 《Plasma Physics Reports》2009,35(2):149-153
Possible schemes of X-ray-activated deexcitation of isomers of rhodium, silver, tellurium, and bismuth are considered. It is shown that conditions necessary for deexcitation of rhodium isomer can, in principle, be achieved in a high-temperature solid-body-density plasma produced by an ultrashort laser pulse. 相似文献
49.
50.
Apurinic and/or apyrimidinic (AP) sites were excised from PM2 phage DNA by two enzymes: an AP endodeoxyribonuclease isolated from rat neocortex chromatin and a rat brain exodeoxyribonuclease, DNase B III. The resulting gap was filled with DNA polymerase beta prepared from rat liver and finally ligated by Escherichia coli DNA ligase. 相似文献