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961.
Ahn YO Zheng M Bevan DR Esen A Shiu SH Benson J Peng HP Miller JT Cheng CL Poulton JE Shih MC 《Phytochemistry》2007,68(11):1510-1520
Catalysing the hydrolysis of terminal beta-galactosyl residues from carbohydrates, galactolipids, and glycoproteins, glycoside hydrolase family 35 (beta-galactosidases; BGALs) are widely distributed in plants and believed to play many key roles, including modification of cell wall components. Completion of the Arabidopsis thaliana genome sequencing project has, for the first time, allowed an examination of the total number, gene structure, and evolutionary patterns of all Family 35 members in a representative (model) angiosperm. Reiterative database searches established a multigene family of 17 members (designated BGAL1-BGAL17). Using these genes as query sequences, BLAST and Hidden Markov Model searches identified BGAL genes among 22 other eukaryotes, whose genomic sequences are known. The Arabidopsis (n=17) and rice (n=15) BGAL families were much larger than those of Chlamydomonas, fungi, and animals (n=0-4), and a lineage-specific expansion of BGAL genes apparently occurred after divergence of the Arabidopsis and rice lineages. All plant BGAL genes, with the exception of Arabidopsis BGAL17 and rice Os 9633.m04334, form a monophyletic group. Arabidopsis BGAL expression levels are much higher in mature leaves, roots, flowers, and siliques but are lower in young seedlings. BGAL8, BGAL11, BGAL13, BGAL14, and BGAL16 are expressed only in flowers. Catalytically active BGAL4 was produced in the E. coli and baculoviral expression systems, purified to electrophoretic homogeneity, and partially characterized. The purified enzyme hydrolyzed p- and o-nitrophenyl-beta-d-galactosides. It also cleaved beta-(1,3)-, beta-(1,4)-, and beta-(1,6)-linked galactobiosides and galactotriosides, showing a marked preference for beta-(1,3)- and beta-(1,4)-linkages. 相似文献
962.
Kobayashi T Lu J Li Z Hung VS Kurata A Hatada Y Takai K Ito S Horikoshi K 《Applied microbiology and biotechnology》2007,75(1):71-80
A new high-alkaline protease (ALTP) was purified to homogeneity from a culture of the strictly anaerobic and extremely alkaliphilic
Alkaliphilus transvaalensis. The molecular mass was 30 kDa on sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The enzyme showed the maximal
caseinolytic activity higher than pH 12.6 in KCl–NaOH buffer at 40°C. Hydrolysis of the oxidized insulin B-chain followed
by mass spectrometric analysis of the cleaved products revealed that as many as 24 of the total 29 peptide bonds are hydrolyzed
in a block-cutting manner, suggesting that ALTP has a widespread proteolytic functions. Calcium ion had no effect on the activity
and stability of ALTP, unlike known subtilisins. The deduced amino acid sequence of the enzyme comprised 279 amino acids plus
97 prepropeptide amino acids. The amino acid sequence of mature ALTP was confirmed by capillary liquid chromatography coupled
to tandem mass spectrometry, which was the 93% coverage of the deduced amino acid sequence. The mature enzyme showed moderate
homology to subtilisin LD1 from the alkaliphilic Bacillus sp. strain KSM-LD1 with 64% identity, and both enzymes formed a new subcluster at an intermediate position among true subtilisins
and high-alkaline proteases in a phylogenetic tree of subtilase family A. ALTP is the first high-alkaline protease reported
from a strict anaerobe in this family. 相似文献
963.
Solution structure of the MID1 B-box2 CHC(D/C)C(2)H(2) zinc-binding domain: insights into an evolutionarily conserved RING fold 总被引:2,自引:0,他引:2
Massiah MA Matts JA Short KM Simmons BN Singireddy S Yi Z Cox TC 《Journal of molecular biology》2007,369(1):1-10
The B-box type 2 domain is a prominent feature of a large and growing family of RING, B-box, coiled-coil (RBCC) domain-containing proteins and is also present in more than 1500 additional proteins. Most proteins usually contain a single B-box2 domain, although some proteins contain tandem domains consisting of both type 1 and type 2 B-boxes, which actually share little sequence similarity. Recently, we determined the solution structure of B-box1 from MID1, a putative E3 ubiquitin ligase that is mutated in X-linked Opitz G/BBB syndrome, and showed that it adopted a betabetaalpha RING-like fold. Here, we report the tertiary structure of the B-box2 (CHC(D/C)C(2)H(2)) domain from MID1 using multidimensional NMR spectroscopy. This MID1 B-box2 domain consists of a short alpha-helix and a structured loop with two short anti-parallel beta-strands and adopts a tertiary structure similar to the B-box1 and RING structures, even though there is minimal primary sequence similarity between these domains. By mutagenesis, ESI-FTICR and ICP mass spectrometry, we show that the B-box2 domain coordinates two zinc atoms with a 'cross-brace' pattern: one by Cys175, His178, Cys195 and Cys198 and the other by Cys187, Asp190, His204, and His207. Interestingly, this is the first case that an aspartic acid is involved in zinc atom coordination in a zinc-finger domain, although aspartic acid has been shown to coordinate non-catalytic zinc in matrix metalloproteinases. In addition, the finding of a Cys195Phe substitution identified in a patient with X-linked Opitz GBBB syndrome supports the importance of proper zinc coordination for the function of the MID1 B-box2 domain. Notably, however, our structure differs from the only other published B-box2 structure, that from XNF7, which was shown to coordinate one zinc atom. Finally, the similarity in tertiary structures of the B-box2, B-box1 and RING domains suggests these domains have evolved from a common ancestor. 相似文献
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965.
966.
967.
Aminoindan and hydroxyaminoindan, metabolites of rasagiline and ladostigil, respectively, exert neuroprotective properties in vitro 总被引:2,自引:0,他引:2
The anti-Parkinson, selective irreversible monoamine oxidase B inhibitor drug, rasagiline (Azilect), recently approved by the US Food and Drug Administration, has been shown to possess neuroprotective-neurorescue activities in in vitro and in vivo models. Recent preliminary studies indicated the potential neuroprotective effect of the major metabolite of rasagiline, 1-(R)-aminoindan. In the current study, the neuroprotective properties of 1-(R)-aminoindan were assessed employing a cytotoxic model of human neuroblastoma SK-N-SH cells in high-density culture-induced neuronal death. We show that aminoindan (0.1-1 mumol/L) significantly reduced the apoptosis-associated phosphorylated protein, H2A.X (Ser139), decreased the cleavage of caspase 9 and caspase 3, while increasing the anti-apoptotic proteins, Bcl-2 and Bcl-xl. Protein kinase C (PKC) inhibitor, GF109203X, prevented the neuroprotection, indicating the involvement of PKC in aminoindan-induced cell survival. Aminoindan markedly elevated pPKC(pan) and specifically that of the pro-survival PKC isoform, PKCepsilon. Additionally, hydroxyaminoindan, a metabolite of a novel bifunctional drug, ladostigil [(N-propargyl-(3R) aminoindan-5yl)-ethyl methyl carbamate], combining cholinesterase and monoamine oxidase inhibitor activity, exerted similar neuroprotective properties. Aminoindan and hydroxyaminoindan also protected rat pheochromacytoma PC-12 cells against the neurotoxin, 6-hydroxydopamine. Our findings suggest that both metabolites may contribute to the overall neuroprotective activity of their respective parent compounds, further implicating rasagiline and ladostigil as potentially valuable drugs for treatment of a wide variety of neurodegenerative disorders of aging. 相似文献
968.
This article concentrates on the care for people who suffer from progressive dementia. Dementia has a great impact on a person’s well‐being as well as on his or her social environment. Dealing with dementia raises moral issues and challenges for participants, especially for family members. One of the moral issues in the care for people with dementia is centred on responsibilities; how do people conceive and determine their responsibilities towards one another? To investigate this issue we use the theoretical perspective of Margaret Walker. She states that ideas about identity play a crucial role in patterns of normative expectations with regard to the distribution of responsibilities in daily practices of care. The results of this study show how the identity of a family‐member is put under pressure and changes during her loved one’s illness that leads to difficulties and misunderstandings concerning the issue of responsibility. These results offer an insight into the complexities of actual practices of responsibility and highlight the importance for those caring for people with dementia of attending carefully to how they see themselves and how they see other people involved (Who am I? Who do I want to be for the other?). Answers to such questions show what people expect from themselves and from one another, and how they, at any rate, are distributing responsibilities in a given situation. Professional caregivers should take into account that family members might have different ideas about who they are and consequently about what their responsibilities are. 相似文献
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970.