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121.
A systematic study was made of the photochemical action of methylene blue on amino acids.Tyrosine, tryptophan, histidine, methionine, and cystine were highly reactive during the photoöxidation; the rest of the amino acids acted sluggishly or not at all.In tyrosine, tryptophan, and histidine, the entire oxygen uptake and CO2 evolution were due to the cyclic nucleus, involving rupture of the rings.During the photochemical action of methylene blue on tyrosine, tryptophan, and methionine, intermediary oxidizing agents were formed; in methionine this was shown to be H2O2.The photoöxidation of methionine resulted in the formation of methionine sulfoxide as an end product.Iodometric titration and measurement of ultraviolet absorption during irradiation of methionine indicate the formation of an intermediary dehydrogenation product which appears to differ from Lavine's dehydromethionine.Cystine was photoöxidized, probably beyond the cysteic acid stage.Peptide bonds did not participate in the photochemical action of methylene blue.Methylation of the α-amino group of lysine to the corresponding secondary and tertiary compounds produced increased reactivity in the photoöxidation. 相似文献
122.
123.
Jurriaan J H?lzenspies Willem Stoorvogel Ben Colenbrander Bernard AJ Roelen Dagmar R Gutknecht Theo van Haeften 《BMC developmental biology》2009,9(1):8
Background
Mammalian oocytes acquire competence to be fertilized during meiotic maturation. The protein kinase CDC2 plays a pivotal role in several key maturation events, in part through controlled changes in CDC2 localization. Although CDC2 is involved in initiation of maturation, a detailed analysis of CDC2 localization at the onset of maturation is lacking. In this study, the subcellular distribution of CDC2 and its regulatory proteins cyclin B and SPDY in combination with several organelle markers at the onset of pig oocyte maturation has been investigated. 相似文献124.
Gwendoline Kint Kathleen AJ Sonck Geert Schoofs David De Coster Jos Vanderleyden Sigrid CJ De Keersmaecker 《BMC microbiology》2009,9(1):198
Background
Quorum sensing is a term describing a bacterial communication system mediated by the production and recognition of small signaling molecules. The LuxS enzyme, catalyzing the synthesis of AI-2, is conserved in a wide diversity of bacteria. AI-2 has therefore been suggested as an interspecies quorum sensing signal. To investigate the role of endogenous AI-2 in protein expression of the Gram-negative pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium), we performed a 2D-DIGE proteomics experiment comparing total protein extract of wildtype S. Typhimurium with that of a luxS mutant, unable to produce AI-2. 相似文献125.
William J Holmes Richard AJ Darby Martin DB Wilks Rodney Smith Roslyn M Bill 《Microbial cell factories》2009,8(1):35-14
Background
The optimisation and scale-up of process conditions leading to high yields of recombinant proteins is an enduring bottleneck in the post-genomic sciences. Typical experiments rely on varying selected parameters through repeated rounds of trial-and-error optimisation. To rationalise this, several groups have recently adopted the 'design of experiments' (DoE) approach frequently used in industry. Studies have focused on parameters such as medium composition, nutrient feed rates and induction of expression in shake flasks or bioreactors, as well as oxygen transfer rates in micro-well plates. In this study we wanted to generate a predictive model that described small-scale screens and to test its scalability to bioreactors. 相似文献126.
127.
van de Loo FA 《Arthritis research & therapy》2011,13(2):111
It has long been recognized that laboratory tests are useful in the diagnosis of disease and to monitor treatment outcome.
Their performance has become even more demanding with the development of personalized medicine. In patients with rheumatoid
arthritis (RA) the standard biochemical tests measure serological markers of disease, such as C-reactive protein, and RA-associated
auto-antibodies, such as rheumatoid factor and anti-citrullinated protein antibodies. The information obtained from these
markers does not, however, provide a complete picture of the disease and treatment efficacy. New biomarkers based on cytokine
receptor complexes are promising for RA theragnostics. 相似文献
128.
We sequenced the entire control region and portions of flanking genes
(tRNA(Phe), tRNA(Glu), and ND6) in the common chaffinch (Fringilla
coelebs), blue chaffinch (F. teydea), brambling (F. montifringilla), and
greenfinch (Carduelis chloris). In these finches the control region is
similar in length (1,223-1,237 bp) and has the same flanking gene order as
in other birds, and contains a putative TAS element and the highly
conserved CSB-1 and F, D, and C boxes recognizable in most vertebrates.
Cloverleaf-like structures associated with the TAS element at the 5' end
and CSB-1 at the 3' end of the control region may be involved with the stop
and start of D-loop synthesis, respectively. The pattern of nucleotide and
substitution bias is similar to that in other vertebrates, and consequently
the finch control region can be subdivided into a central, conserved G-rich
domain (domain II) flanked by hypervariable 5'-C-rich (domain I) and
3'-AT-rich (domain III) segments. In pairwise comparisons among finch
species, the central domain has unusually low transition/transversion
ratios, which suggests that increased G + T content is a functional
constraint, possibly for DNA primase efficiency. In finches the relative
rates of evolution vary among domains according to a ratio of 4.2 (domain
III) to 2.2 (domain I) to 1 (domain II), and extensively among sites within
domains I and II. Domain I and III sequences are extremely useful in
recovering intraspecific phylogeographic splits between populations in
Africa and Europe, Madeira, and a basal lineage in Nefza, Tunisia. Domain
II sequences are highly conserved, and are therefore only useful in
conjunction with sequences from domains I and III in phylogenetic studies
of closely related species.
相似文献
129.
130.
MIKOAJ K. ZAPALSKI 《Palaeontology》2007,50(6):1375-1380
Abstract: Tube-like traces of organisms belonging to the ichnogenus Chaetosalpinx Sokolov have been considered in the literature as commensal endobiontic organisms of tabulate corals. Their position between the corallites (or sometimes within the septa), perforation of the host's skeleton and soft tissue, modification of its phenotype and a possible inhibition of its growth show that the relationship between these organisms and tabulate corals can best be interpreted as parasitism rather than commensalism, as previously suggested. Such an interpretation may be extended to the ichnogenera Helicosalpinx Oekentorp and Actinosalpinx Sokolov, which show identical placement within the host colony and similar features, such as the absence of their own wall. 相似文献