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161.
162.
163.
Huet J Wyckmans J Wintjens R Boussard P Raussens V Vandenbussche G Ruysschaert JM Azarkan M Looze Y 《Cellular and molecular life sciences : CMLS》2006,63(24):3042-3054
Two chitinases, able to use tetra-N-acetylglucosamine, chitin and chitosan as substrates, were characterized after purification from Carica papaya latex. The complete amino acid sequence of the major form and about 40% of the minor one were determined through proteolytic
digestions and mass spectroscopy analysis. Sequencing demonstrated that both papaya chitinases are members of the family 19
of glycosyl hydrolases (GH19). Based on the known 3-D structures of other members of family GH19, it was expected that papaya
chitinases would adopt all-alpha structures. However, circular dichroism and infrared spectroscopy indicated, for the papaya
chitinases, a content of 15–20% of extended structures besides the expected 40% of alpha helices. Since the fully sequenced
papaya chitinase contains a large number of proline residues the possibility that papaya chitinase contains polyproline II
stretches was examined in the context of their resistance against proteolytic degradation.
Received 11 July 2006; received after revision 13 October 2006; accepted 25 October 2006 相似文献
164.
Kramer J Böhrnsen F Lindner U Behrens P Schlenke P Rohwedel J 《Cellular and molecular life sciences : CMLS》2006,63(5):616-626
Microfracture of subchondral bone results in intrinsic repair of cartilage defects. Stem or progenitor cells from bone marrow
have been proposed to be involved in this regenerative process. Here, we demonstrate for the first time that mesenchymal stem
(MS) cells can in fact be recovered from matrix material saturated with cells from bone marrow after microfracture. This also
introduces a new technique for MS cell isolation during arthroscopic treatment. MS cells were phenotyped using specific cell
surface antibodies. Differentiation of the MS cells into the adipogenic, chondrogenic and osteogenic lineage could be demonstrated
by cultivation of MS cells as a monolayer, as micromass bodies or mesenchymal microspheres. This study demonstrates that MS
cells can be attracted to a cartilage defect by guidance of a collagenous matrix after perforating subchondral bone. Protocols
for application of MS cells in restoration of cartilage tissue include an initial invasive biopsy to obtain the MS cells and
time-wasting in vitro proliferation and possibly differentiation of the cells before implantation. The new technique already includes attraction
of MS cells to sites of cartilage defects and therefore may overcome the necessity of in vitro proliferation and differentiation of MS cells prior to transplantation.
Received 3 November 2005; received after revision 15 December 2005; accepted 4 January 2006 相似文献
165.
Pappas G Panagopoulou P Christou L Akritidis N 《Cellular and molecular life sciences : CMLS》2006,63(19-20):2229-2236
Brucella has traditionally been considered a biological weapon. It was the subject of extensive offensive research in the past, and still belongs to category B pathogens on most lists. Its propensity for airborne transmission and induction of chronic debilitating disease requiring combined antibiotic regimens for treatment, its abundance around the world and its vague clinical characteristics defying rapid clinical diagnosis are some of the characteristics that apply to the pathogen's weapons potential. Yet minimal mortality, availability of treatment options, protracted inoculation period and the emergence of new, more virulent potential weapons means that its inclusion among agents of bioterrorism is nowadays mainly of historical significance. Nevertheless, in the interest of literacy and of avoiding panic, physicians and the public both should be aware of the most common zoonosis worldwide. 相似文献
166.
Betaine homocysteine S-methyltransferase: just a regulator of homocysteine metabolism? 总被引:1,自引:0,他引:1
Betaine homocysteine methyltransferase (BHMT), a Zn2+-dependent thiolmethyltransferase, contributes to the regulation of homocysteine levels, increases in which are considered
a risk factor for cardiovascular diseases. Most plasma homocysteine is generated through the liver methionine cycle, in which
BHMT metabolizes approximately 25% of this non-protein amino acid. This process allows recovery of one of the three methylation
equivalents used in phosphatidylcholine synthesis through transmethylation, a major homocysteine-producing pathway. Although
BHMT has been known for over 40 years, the difficulties encountered in its isolation precluded detailed studies until very
recently. Thus, the last 10 years, since the sequence became available, have yielded extensive structural and functional data.
Moreover, recent findings offer clues for potential new functions for BHMT. The purpose of this review is to provide an integrated
view of the knowledge available on BHMT, and to analyze its putative roles in other processes through interactions uncover
to date.
Received 26 May 2006; received after revision 3 July 2006; accepted 24 August 2006 相似文献
167.
Expansion of amino acid homo-sequences, such as polyglutamines or polyalanines, in proteins has been directly implicated in
various degenerative diseases through a mechanism of protein misfolding and aggregation. However, it is still unclear how
the nature of the expansion and the protein context influence the tendency of a protein to aggregate. Here, we have addressed
these questions using spinocerebellar ataxia type-3 (ATX3) protein, the best characterised of the polyglutamine proteins,
chosen as a model system. Using a transfected mammalian cell line, we demonstrate that ATX3 aggregation is noticeably reduced
by deletion or replacement of regions other than the polyglutamine tract. The nature of the amino acid homo-sequences also
has a strong influence on aggregation. From our studies, we draw general conclusions on the effect of the protein architecture
and of the amino acid homo-sequence on pathology.
Received 3 March 2006; received after revision 19 April 2006; accepted 22 May 2006 相似文献
168.
Temussi PA 《Cellular and molecular life sciences : CMLS》2006,63(16):1876-1888
A few proteins, discovered mainly in tropical fruits, have a distinct sweet taste. These proteins have played an important
role towards a molecular understanding of the mechanisms of taste. Owing to the huge difference in size, between most sweeteners
and sweet proteins, it was believed that they must interact with a different receptor from that of small molecular weight
sweeteners. Recent modelling studies have shown that the single sweet taste receptor has multiple active sites and that the
mechanism of interaction of sweet proteins is intrinsically different from that of small sweeteners. Small molecular weight
sweeteners occupy small receptor cavities inside two subdomains of the receptor, whereas sweet proteins can interact with
the sweet receptor according to a mechanism called the ‘wedge model’ in which they bind to a large external cavity. This review
describes these mechanisms and outlines a history of sweet proteins.
Received 11 February 2006; received after revision 31 March 2006; accepted 11 May 2006 相似文献
169.
Common loss-of-function variants of the epidermal barrier protein filaggrin are a major predisposing factor for atopic dermatitis 总被引:21,自引:0,他引:21
Palmer CN Irvine AD Terron-Kwiatkowski A Zhao Y Liao H Lee SP Goudie DR Sandilands A Campbell LE Smith FJ O'Regan GM Watson RM Cecil JE Bale SJ Compton JG DiGiovanna JJ Fleckman P Lewis-Jones S Arseculeratne G Sergeant A Munro CS El Houate B McElreavey K Halkjaer LB Bisgaard H Mukhopadhyay S McLean WH 《Nature genetics》2006,38(4):441-446
Atopic disease, including atopic dermatitis (eczema), allergy and asthma, has increased in frequency in recent decades and now affects approximately 20% of the population in the developed world. Twin and family studies have shown that predisposition to atopic disease is highly heritable. Although most genetic studies have focused on immunological mechanisms, a primary epithelial barrier defect has been anticipated. Filaggrin is a key protein that facilitates terminal differentiation of the epidermis and formation of the skin barrier. Here we show that two independent loss-of-function genetic variants (R510X and 2282del4) in the gene encoding filaggrin (FLG) are very strong predisposing factors for atopic dermatitis. These variants are carried by approximately 9% of people of European origin. These variants also show highly significant association with asthma occurring in the context of atopic dermatitis. This work establishes a key role for impaired skin barrier function in the development of atopic disease. 相似文献
170.
The detection of sequence variation, for which DNA sequencing has emerged as the most sensitive and automated approach, forms the basis of all genetic analysis. Here we describe and illustrate an algorithm that accurately detects and genotypes SNPs from fluorescence-based sequence data. Because the algorithm focuses particularly on detecting SNPs through the identification of heterozygous individuals, it is especially well suited to the detection of SNPs in diploid samples obtained after DNA amplification. It is substantially more accurate than existing approaches and, notably, provides a useful quantitative measure of its confidence in each potential SNP detected and in each genotype called. Calls assigned the highest confidence are sufficiently reliable to remove the need for manual review in several contexts. For example, for sequence data from 47-90 individuals sequenced on both the forward and reverse strands, the highest-confidence calls from our algorithm detected 93% of all SNPs and 100% of high-frequency SNPs, with no false positive SNPs identified and 99.9% genotyping accuracy. This algorithm is implemented in a software package, PolyPhred version 5.0, which is freely available for academic use. 相似文献