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1.
Srinivasulu S Perumalsamy K Upadhya R Manjula BN Feiring S Alami R Bouhassira E Fabry ME Nagel RL Acharya AS 《The protein journal》2006,25(7-8):503-516
The linkage of pair-wise interactions of contact site mutations of HbS has been studied using Le Lamentin [His-20 (α)→Gln], Hoshida [Glu-43 (β)→Gln] and α2β2T87Q mutations as the prototype of three distinct classes of contact sites of deoxy HbS fiber. Binary mixture experiments established that βA-chain with the Thr-87 (β)→Gln mutation is as potent as the γ-chain of HbF (α2γ2) in inhibiting polymerization. On combining the influence of Le Lamentin mutation with that of β2T87Q mutations; the net influence is only partial additivity. On the other hand, in binary mixture studies, combined influence of Hoshida mutation with that of β2T87Q mutations is synergistic. Besides, a significant level of synergistic complementation is also seen when the Le Lamentin and Hoshida mutations are combined in HbS (symmetrical tetramers). Le Lamentin and Hoshida mutation introduced into the cis-dimer of the asymmetric hybrid tetramer completely neutralizes the Val-6 (β) dependent polymerization. Accordingly, we propose that combining the perturbation of intra-double strand contact site with that of an inter-double strand contact site exhibit synergy when they are present in two different chains of the αβ dimer. A comparison of the present results with that of the earlier studies suggest that when the two contact site perturbations are from the same sub-unit of the αβ dimer only partial additivity is observed. The map of interaction linkage of the contact site mutations exposes new strategies in the design of novel anti-sickling Hbs for the gene therapy of sickle cell disease. 相似文献
2.
With yeast two-hybrid methods, we used a C-terminal fragment (residues 1697–2145) of non-erythroid beta spectrin (βII-C),
including the region involved in the association with alpha spectrin to form tetramers, as the bait to screen a human brain
cDNA library to identify proteins interacting with βII-C. We applied stringent selection steps to eliminate false positives
and identified 17 proteins that interacted with βII-C (IPβII-C s). The proteins include a fragment (residues 38–284) of “THAP domain containing, apoptosis associated protein 3, isoform
CRA g”, “glioma tumor suppressor candidate region gene 2” (residues 1-478), a fragment (residues 74–442) of septin 8 isoform
c, a fragment (residues 704–953) of “coatomer protein complex, subunit beta 1, a fragment (residues 146–614) of zinc-finger
protein 251, and a fragment (residues 284–435) of syntaxin binding protein 1. We used yeast three-hybrid system to determine
the effects of these βII-C interacting proteins as well as of 7 proteins previously identified to interact with the tetramerization
region of non-erythroid alpha spectrin (IPαII-N s) [1] on spectrin tetramer formation. The results showed that 3 IPβII-C s were able to bind βII-C even in the presence of αII-N, and 4 IPαII-N s were able to bind αII-N in the presence of βII-C. We also found that the syntaxin binding protein 1 fragment abolished
αII-N and βII-C interaction, suggesting that this protein may inhibit or regulate non-erythroid spectrin tetramer formation. 相似文献
3.
Robert P. Burns Jr. Kannan Natarajan Nicola J. H. LoCascio David P. O′Brien Joan A. Kobori Nilabh Shastri R. K. Barth 《Immunogenetics》1997,47(2):107-114
The influence of β-chain diversity on the expressed T-cell receptor (TCR) α-chain repertoire was investigated using transgenic
mice which exclusively express a single rearranged TCR β-chain gene. Analysis of these mice using α-chain-specific recombinant
cDNA libraries showed that expression of the transgene-encoded β chain results in significant skewing in Tcra-V gene segment usage vs nontransgenic mice. Skewing was most pronounced towards α chains using TCRA-V segments. Sequence analysis of Tcra-V8-containing genes from transgenic T cells revealed predominant use of a single Tcra-J segment (Tcra-J24), which was not detected in Tcra-V8 containing genes isolated from nontransgenic T cells. Further analysis revealed that co-expression of Tcra-V8 with Tcra-J24 in β-transgenic mice is exhibited almost exclusively by CD4+ T cells, and is associated with a limited number of closely related N-regions. Analysis of transgenic CD8+ T cells demonstrated predominant co-expression of Tcra-V8 with another Tcra-J (Tcra-J30), together with a different, limited N-region sequence. We conclude that the composition of expressed β chains can profoundly
influence the selection of companion α chains expressed in the periphery, and that α-chain N and J regions play a crucial
role in discriminating between class I vs class II major histocompatibility complex (MHC)-restricted recognition. Further,
these results are in agreement with recent data concerning the crystal structure of the TCR, and most consistent with a model
for TCR structure in which the complementarity determining region (CDR)3α domain participates in direct contact with the MHC.
Received: 28 January 1997 / Revised: 22 July 1997 相似文献
4.
Consensus amino acid sequences of FADH2-dependent bacterial halogenases were used to design PCR primers amplifying a halogenase gene fragment from the chloramphenicol
producer Streptomyces venezuelae ISP5230. The sequence-specific degenerate primers (MPF1 and MPR2) were used with a touchdown PCR procedure in the first PCR-assisted
cloning of a halogenase gene fragment. In the region of the 290-bp PCR product containing the reverse primer, the deduced
amino acid sequence exhibited characteristics of a β–α–β fold present in FAD-binding sites of certain monooxygenases. When
used to probe Southern blots of restriction-enzyme-digested DNA, the [α-32P]dCTP-labeled PCR product hybridized specifically with DNA fragments from genomic DNA of S. venezuelae ISP5230. Primers MPF1 and MPR2 also allowed amplification by PCR of approximately 290-bp DNA fragments from several other
streptomycetes. The fragments from Streptomyces aureofaciens NRRL2209 and Streptomyces coelicolor A3(2) showed sequence identity with halogenase genes from these species. Thus, the PCR primers are of potential value for
amplification and subsequent isolation of actinomycete halogenase genes. Journal of Industrial Microbiology & Biotechnology (2002) 29, 1–5 doi:10.1038/sj.jim.7000263
Received 25 June 2001/ Accepted in revised form 02 April 2002 相似文献
5.
Yeast two-hybrid (Y2H) and isothermal titration calorimetry (ITC) methods were used to further study the mutational effect
of non-erythroid alpha spectrin (αII) at position 22 in tetramer formation with beta spectrin (βII). Four mutants, αII-V22D,
V22F, V22M and V22W, were studied. For the Y2H system, we used plasmids pGBKT7, consisting of the cDNA of the first 359 residues
at the N-terminal region of αII, and pGADT7, consisting of the cDNA of residues 1697–2145 at the C-terminal region of βII.
Strain AH109 yeast cells were used for colony growth assays and strain Y187 was used for β-galactosidase activity assays.
Y2H results showed that the C-terminal region of βII interacts with the N-terminal region of αII, either the wild type, or
those with V22F, V22M or V22W mutations. The V22D mutant did not interact with βII. For ITC studies, we used recombinant proteins
of the αII N-terminal fragment and of the erythroid beta spectrin (βI) C-terminal fragment; results showed that the Kd values for V22F were similar to those for the wild-type (about 7 nM), whereas the Kd values were about 35 nM for V22M and about 90 nM for V22W. We were not able to detect any binding for V22D with ITC methods.
This study clearly demonstrates that the single mutation at position 22 of αII, a region critical to the function of nonerythroid
α spectrin, may lead to a reduced level of spectrin tetramers and abnormal spectrin-based membrane skeleton. These abnormalities
could cause abnormal neural activities in cells. 相似文献
6.
G. E. Osman Mark C. Hannibal Jon P. Anderson Saijai Cheunsuk Stephen R. Lasky H. Denny Liggitt Warren C. Ladiges Leroy E. Hood 《Immunogenetics》1999,49(9):764-772
Collagen type II-induced arthritis (CIA) develops in susceptible mouse strains after intradermal injections of type II collagen
(CII) in complete Freund's adjuvant (CFA). Susceptibility to CIA in mice is linked to genes of the major histocompatibility
complex (MHC). Although the SWR mouse has a susceptible MHC haplotype (H2
q
), it is resistant to CIA. SWR exhibits at least two known immunological defects: (1) it contains a germline deletion of about
50% of T-cell receptor (TCR) Vβ-chain gene segments, and (2) SWR is deficient in complement component C5. It has been shown
that T cells that express TCRVα11.1 and TCRVβ8.2 play a substantial role in the pathogenesis of arthritis in the DBA/1 mouse
(H2
q
). We generated SWR transgenic (tg) mice to determine whether the expression of pathogenic Vα11.1 and/or Vβ8.2 transgenes
would confer arthritis susceptibility. Arthritis was induced in the SWR TCRαβ tg mice, but not in SWR TCRβ tg mice. To address
the role of Vα11.1 in arthritis susceptibility, we examined the allelic polymorphisms of the Tcra-V11-gene subfamily members between the arthritis susceptible DBA/1 mouse and the arthritis-resistant SWR mouse strain. The amino
acid sequences of the Vα11.1 alleles differ at two positions (codons 18 and 68). Accordingly, these two amino acid changes are sufficient to allow the
production of pathogenic T cells in SWR mice. This is the first demonstration of the association of a particular Tcra-V allele and arthritis susceptibility in mice.
Received: 20 November 1998 / Revised: 15 February 1999 相似文献
7.
L. F. Canosa A. G. Pozzi N. R. Ceballos 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(7):491-496
Sliced testis tissue from Bufo arenarum was incubated in the presence of [3H]pregnenolone. Testis fragments were also used for double isotope experiments using [3H]pregnenolone and [14C]progesterone. Specific activities were equated with the addition of radioinert pregnenolone. When yields of radiometabolites
were analysed, pregnenolone was found to be a good precursor for C19 steroids such as dehydroepiandrosterone, 5-androsten-3β,17β diol, testosterone, 5α-dihydrotestosterone and a C21 steroid, 5α-pregnan-3,20 dione. Progesterone mainly converts to 5α-pregnan-3,20 dione, a steroid with unknown function in
amphibians. The 5-ene pathway, including 5-androsten-3β,17β diol as intermediate, could be predominant for androgen biosynthesis.
Testes bypass not only progesterone but also androstenedione for testosterone biosynthesis.
Accepted: 17 April 1998 相似文献
8.
Killing of wild-type spores of Bacillus subtilis by t-butyl hydroperoxide, cumene hydroperoxide and peracetic acid was not through DNA damage, as shown by the absence of mutations
in the survivors and the identical sensitivity of spores of strains with or without a recA mutation. In contrast, B. subtilis spores (termed α−β−) lacking the DNA protective α/β-type small, acid-soluble spore proteins (SASP) were more sensitive to t-butyl hydroperoxide and cumene hydroperoxide, and their killing was in large part through DNA damage, as shown by the high
frequency of mutations in the survivors and the greater sensitivity of α−β− recA spores. Analysis of t-butyl hydroperoxide-treated spores showed that generation of DNA damage in α−β− spores was more rapid than in wild-type spores; α/β-type SASP also protected against DNA strand breakage in vitro caused by t-butyl hydroperoxide. α/β-Type SASP appeared to play no role in protection of spores from killing by peracetic acid; wild-type
and α−β− spores exhibited identical peracetic acid sensitivity and their killing by this agent appeared to be not through DNA damage.
Received 17 December 1996/ Accepted in revised form 13 March 1997 相似文献
9.
Haptoglobin (Hp) is a hemoglobin-binding plasma protein consisting of two types of chains, called α and β, which originate
from a common polypeptide. In humans, but not in other mammals, Hp has been shown to occur in two allelic forms, Hp1 and Hp2,
which differ in the length of the α-chain. The longer α-chain (in Hp2) seems to have arisen by an internal duplication of
a gene segment coding for almost the entire α-chain of Hp1. In this article we show that Hp of cow (Bos taurus) contains an α-chain, the structure of which is similar to that of the human Hp2 α-chain. Furthermore, comparison of the
structure of bovine Hp and human Hp2 suggests that the bovine gene arose by a duplication of the gene segment homologous to that duplicated in human Hp2. However, a phylogenetic analysis indicates that the two genes were formed independently. The evolutionary pressure that
has led to the fixation of the Hps with a longer α-chain is not known.
Reviewing
Editor: Dr. Manyuan Long 相似文献
10.
By the use of the Immobiline technique at pH ranges 7.0–7.6 and 6.9–7.9, 16 different hemoglobin (Hb) phenotypes were observed
in 61 English Saanen goats. They are explained in this breed by a genetic theory of five β-globin genes (A
4,A
6,A
8,E, andD) and two closely linked α-globin loci (′α and ″α) of which the ″α has a variant allele, provisionally called ″α
X
. Family data together with observed and expected Hb frequencies were in agreement with the genetic theory. Among six Barbary
sheep there were three Hb phenotypes explained by the occurrence of the β-chain allelesB andC
na. 相似文献
11.
Jianxia Kang Yuanli Song Akin Sevinc Leslie W.-M. Fung 《Cellular & molecular biology letters》2010,15(1):46-54
Spectrin tetramerization is important for the erythrocyte to maintain its unique shape, elasticity and deformability. We used
recombinant model proteins to show the importance of one residue (G46) in the erythroid α-spectrin junction region that affects
spectrin tetramer formation. The G46 residue in the erythroid spectrin N-terminal junction region is the only residue that
differs from that in non-erythroid spectrin. The corresponding residue is R37. We believe that this difference may be, at
least in part, responsible for the 15-fold difference in the equilibrium constants of erythroid and non-erythroid tetramer
formation. In this study, we replaced the Gly residue with Ala, Arg or Glu residues in an erythroid α-spectrin model protein
to give G46A, G46R or G46E, respectively. We found that their association affinities with a β-spectrin model protein were
quite different from each other. G46R exhibited a 10-fold increase and G46E exhibited a 16-fold decrease, whereas G46A showed
little difference, when compared with the wild type. The thermal and urea denaturation experiments showed insignificant structural
change in G46R. Thus, the differences in affinity were due to differences in local, specific interactions, rather than conformational
differences in these variants. An intra-helical salt bridge in G46R may stabilize the partial domain single helix in α-spectrin,
Helix C’, to allow a more stable helical bundling in the αβ complex in spectrin tetramers. These results not only showed the
importance of residue G46 in erythroid α-spectrin, but also provided insights toward the differences in association affinity
between erythroid and non-erythroid spectrin to form spectrin tetramers. 相似文献
12.
Kanai TH Tanioka Y Tanigawa M Matsumoto Y Ueda S Onodera T Matsumoto Y 《Immunogenetics》1999,50(5-6):295-300
The loci encoding the β chain of the pig major histocompatibility complex (MHC) class II antigens, SLA-DR and -DQ, have been
known to exhibit a remarkable degree of allelic polymorphism. Here, to understand the generation of SLA class II polymorphism, 25 SLA-DRB1 and 24 SLA-DQB genes including newly identified 12 SLA-DRB1 and 7 SLA-DQB genes obtained from miniature pigs were analyzed based on the nucleotide and deduced amino acid sequences. Most of the allelic
diversity was attributed to the variable sequences which encode a β1 domain consisting of a β-pleated sheet followed by an α helix. In the β1 domain coding region, there were four GC-rich sequences, which have been considered to involve the intra-exon sequence exchange
also in other gene evolutions. The first and second GC-rich sequences were χ-like sequences, which have been shown to be a
putative recombination signal, and were stably conserved among SLA-DRB1 and DQB genes. These χ-like sequences identified in SLA-DRB1 and SLA-DQB were found to encode the first turning point of the β-pleated sheet and the boundary between the β-pleated sheet and the
α helix. Analysis of clustered sequence variation also suggested intra-exon gene conversions in which the χ-like sequences
act as putative breakpoints. In addition to point mutations and selection mechanism, intra-exon gene conversions must be an
important mechanism in the generation of allelic polymorphism at the SLA-DRB1 and SLA-DQB.
Received: 3 December 1998 / Revised: 29 June 1999 相似文献
13.
In maturing seed cells, proteins that accumulate in the protein storage vacuoles (PSVs) are synthesized on the endoplasmic reticulum (ER) and transported by vesicles to the PSVs. Vacuolar sorting determinants (VSDs) which are usually amino acid sequences of short or moderate length direct the proteins to this pathway. VSDs identified so far are classified into two types: sequence specific VSDs (ssVSDs) and C-terminal VSDs (ctVSDs). We previously demonstrated that VSDs of α′ and β subunits of β-conglycinin, one of major storage proteins of soybean (Glycine max), reside in the C-terminal ten amino acids. Here we show that both types of VSDs coexist within this region of the α′ subunit. Although ctVSDs can function only at the very C-termini of proteins, the C-terminal ten amino acids of α′ subunit directed green fluorescent protein (GFP) to the PSVs even when they were placed at the N-terminus of GFP, indicating that an ssVSD resides in the sequence. By mutation analysis, it was found that the core sequence of the ssVSD is Ser-Ile-Leu (fifth to seventh residues counted from the C-terminus) which is conserved in the α and β subunits and some vicilin-like proteins. On the other hand, the sequence composed of the C-terminal three amino acids (AFY) directed GFP to the PSVs when it was placed at the C-terminus of GFP, though the function as a VSD was disrupted at the N-terminus of GFP, indicating that the AFY sequence is a ctVSD. 相似文献
14.
Ramunas Rolius Chloe Antoniou Lidia A. Nazarova Stephen H. Kim Garrett Cobb Pooja Gala Priyanka Rajaram Qufei Li Leslie W.-M. Fung 《Cellular & molecular biology letters》2010,15(3):395-405
Calpains and caspases are ubiquitous cysteine proteases that are associated with a variety of cellular pathways. Calpains
are involved in processes such as long term potentiation, cell motility and apoptosis, and have been shown to cleave non-erythroid
(brain) α- and β-spectrin and erythroid β-spectrin. The cleavage of erythroid α-spectrin by calpain has not been reported.
Caspases play an important role in the initiation and execution of apoptosis, and have been shown to cleave non-erythroid
but not erythroid spectrin. We have studied the effect of spectrin fragments on calpain and caspase activities. The erythroid
and non-erythroid spectrin fragments used were from the N-terminal region of α-spectrin, and C-terminal region of β-spectrin,
both consisting of regions involved in spectrin tetramer formation. We observed that the all spectrin fragments exhibited
a concentration-dependent inhibitory effect on calpain, but not caspase activity. It is clear that additional studies are
warranted to determine the physiological significance of calpain inhibition by spectrin fragments. Our findings suggest that
calpain activity is modulated by the presence of spectrin partial domains at the tetramerization site. It is not clear whether
the inhibitory effect is substrate specific or is a general effect. Further studies of this inhibitory effect may lead to
the identification and development of new therapeutic agents specifically for calpains, but not for caspases. Proteins/peptides
with a coiled coil helical conformation should be studied for potential inhibitory effects on calpain activity. 相似文献
15.
16.
Han-liang Cheng Si-ping Sun Yong-xing Peng Xiao-yun Shi Xin Shen Xue-ping Meng Zhi-guo Dong 《Molecular biology reports》2010,37(6):2665-2673
A full-length cDNA coding lipoprotein lipase (LPL) was cloned from liver of adult common carp (Cyprinus carpio Var. Jian) by RT-PCR and rapid amplification of cDNA ends (RACE) approaches. The cDNA obtained was 2,411 bp long with a 1,524 bp
open reading frame (ORF) encoding 507 amino acids. This amino acid sequence contains two structural regions: N-terminus (24–354
residues) and C-terminus (355–507 residues). Before N-terminus, 1–23 residues is signal peptide, 6–23 residues is transmembrance
helix. At N-terminus, some conversed functional sites were found, including two N-linked glycosylation sites Asn41 and Asn88; one catalytic triad Ser174, Asp198 and His283; one conserved heparin-binding site Arg321 to Arg324 (RKNR); eight cysteines residues Cys69 and Cys82, Cys258 and Cys281, Cys306 and Cys325, Cys317 and Cys320 which are involved in four disulfide bridges; one polypeptide “lid” that participates in substrate specificity. At C-terminus,
Asn401 is another N-linked glycosylation site, and Trp434 and Trp435 (WW) is lipid-binding site. The amino acid sequence has a high similarity, and shows similar structural features to LPL of
other species. Tissue distribution of LPL mRNA in liver, head kidney, mesenteric adipose tissue, heart and white muscle of common carp was analyzed by semi-quantitative
RT-PCR method using β-actin gene as internal control. The result showed that the expressions of LPL mRNA were detected in all examined tissues of common carp. The expression levels of LPL in the mesenteric adipose tissue was highest among these tissues, following in liver and head kidney, and the lowest expression
was found in heart and white muscle. 相似文献
17.
Faramarzi MA Yazdi MT Jahandar H Amini M Monsef-Esfahani HR 《Journal of industrial microbiology & biotechnology》2006,33(9):725-733
The strain of Acremonium strictum PTCC 5282 was applied to investigate the biotransformation of androst-1,4-dien-3,17-dione (I; ADD). Microbial products obtained were purified by preparative TLC and the pure metabolites were characterized on the basis of their spectroscopic features (13C NMR, 1H NMR, FTIR, MS) and physical constants (melting points and optical rotations). The 15α-Hydroxyandrost-1,4-dien-3,17-dione (II), 17β-hydroxyandrost-1,4-dien-3-one (III), androst-4-en-3,17-dione (IV; AD), 15α-hydroxyandrost-4-en-3,17-dione (V), 15α,17β-dihydroxyandrost-1,4-dien-3-one (VI) and testosterone (VII) were produced during this fermentation. Formation of the 15α,17β-dihydroxy derivative of ADD is reported for the first time during steroid biotransformation. The bioconversion reactions observed were 1,2-hydrogenation, 15α-hydroxylation and 17-ketone reduction. From the time course profile of this biotransformation, ketone reduction and 1,2-hydrogenation were observed from the first day of fermentation while 15α-hydroxylation occurred from the third day. Optimum concentration of the substrate, which gave the maximum bioconversion efficiency, was 0.5 mg ml−1 in one batch. The highest yield of the microbial products recorded in this work was achieved within the pH range 6.5–7.3 and at the temperature of 27 °C. 相似文献
18.
M. J. Pettinari G. J. Vazquez N. Krüger P. S. Vary A. Steinbüchel B. S. Méndez 《Applied microbiology and biotechnology》1998,49(6):737-742
A Bacillus megaterium genomic fragment, which encoded an activator homologous to σ54 regulators and which was capable of activating Escherichia coli ato genes in trans, was detected in a gene library of B.␣megaterium screened for β-ketothiolase activity. The fragment presented only one complete open reading frame (ORF1), which encoded a
protein of 398 amino acids. The recombinant plasmid complemented mutations in the Escherichia coli atoC regulatory gene. The constitutive expression of the E. coli ato operon mediated by ORF1 could be useful for the synthesis of polyhydroxyalkanoates with different flexibility properties
by recombinant E. coli strains.
Received: 20 October 1997 / Received revision: 18 February 1998 / Accepted: 23 February 1998 相似文献
19.
Thomas A. Gorr Barbara K. Mable Traute Kleinschmidt 《Journal of molecular evolution》1998,47(4):471-485
Phylogenetic relationships among reptiles were examined using previously published and newly determined hemoglobin sequences.
Trees reconstructed from these sequences using maximum-parsimony, neighbor-joining, and maximum-likelihood algorithms were
compared with a phylogenetic tree of Amniota, which was assembled on the basis of published morphological data. All analyses differentiated α chains into αA and αD types, which are present in all reptiles except crocodiles, where only αA chains are expressed. The occurrence of the αD chain in squamates (lizards and snakes only in this study) appears to be a general characteristic of these species. Lizards
and snakes also express two types of β chains (βI and βII), while only one type of β chain is present in birds and crocodiles.
Reconstructed hemoglobin trees for both α and β sequences did not yield the monophyletic Archosauria (i.e., crocodilians + birds) and Lepidosauria (i.e., Sphenodon+ squamates) groups defined by the morphology tree. This discrepancy, as well as some other poorly resolved nodes, might be
due to substantial heterogeneity in evolutionary rates among single hemoglobin lineages. Estimation of branch lengths based
on uncorrected amino acid substitutions and on distances corrected for multiple substitutions (PAM distances) revealed that
relative rates for squamate αA and αD chains and crocodilian β chains are at least twice as high as those of the rest of the chains considered. In contrast to
these rate inequalities between reptilian orders, little variation was found within squamates, which allowed determination
of absolute evolutionary rates for this subset of hemoglobins. Rate estimates for hemoglobins of lizards and snakes yielded
1.7 (αA) and 3.3 (β) million years/PAM when calibrated with published divergence time vs. PAM distance correlates for several speciation
events within snakes and for the squamate ↔ sphenodontid split. This suggests that hemoglobin chains of squamate reptiles
evolved ∼3.5 (αA) or ∼1.7 times (β) faster than their mammalian equivalents. These data also were used to obtain a first estimate of some
intrasquamate divergence times.
Received: 15 September 1997 / Accepted: 4 February 1998 相似文献
20.
E. V. Levina D. L. Aminin S. N. Kovalchuk V. B. Kozhemyako S. A. Dyshlovoi A. I. Kalinovskii P. S. Dmitrenok 《Russian Journal of Bioorganic Chemistry》2010,36(2):233-239
Four polyhydroxylated steroids, new (20R)-5α-cholestan-3β,6α,8,15α,24,26-hexaol (I) and known (20R,25S)-5α-cholestan-3β,6α,8,15β,16β,26-hexaol, (20R,25S)-5α-cholestan-3β,6α,15β,16β,26-pentaol, and marthasterone sulfate were isolated from the Solaster endeca starfish inhabiting the Sea of Okhotsk and characterized. Steroid (I) contains a 24,26-dihydroxylated side chain, which is unique for starfish polyols. The isolated steroids and related metabolites
from two starfish species of the Evasterias genus (in total, 15 compounds) were weakly cytotoxic in a human HeLa cell culture and some of them were inhibitors of non-specific
esterase from mouse Ehrlich carcinoma. The effects of these compounds on the p53 protein activity were studied in a yeast
two-hybrid test system and both inhibitors and stimulators of this activity were found among them. 相似文献