Homogenization analysis

The linear elastic analysis of homogeneous, isotropic cracked bodies started in the 1900s. The existence of three dimensional corner point effects in the vicinity of a corner point where a crack front intersects a free surface was investigated in the late 1970s. An approximate solution by Bažant and Estenssoro explained some features of corner point effects but there were various paradoxes and inconsistencies.

10p tohitohi 19-05-2020 22 3   Download

This article deals with the thermoelastic interaction in a three-dimensional homogeneous and isotropic viscoelastic medium under the Dual-phase-lag model of generalized thermoelasticity. The resulting non-dimensional coupled equations are applied to a specific problem of a half-space whose surface is traction-free and is subjected to a time-dependent thermal shock.

14p tohitohi 19-05-2020 12 1   Download

This paper presents two parameter foundation models for free vibration analysis of non-homogeneous orthotropic rectangular plate resting on elastic foundation whose concept is extensively used in engineering practice.

12p tohitohi 19-05-2020 16 2   Download

Manganese lipoxygenase was isolated to homogeneity from the take-all fungus, Gaeumannomyces graminis. The C-terminal amino acids and several internal peptides were sequenced, and the information was used to obtain a cDNA probe by RT/PCR. Screening of a genomic library of G. graminis yielded a full-length clone of the Mn-Lipoxygenase gene. cDNA analysis showed that the gene spanned 2.6 kb and contained one intron (133 bp). Northern blot analyses indicated two transcripts (2.7 and 3.1 kb). The deduced amino-acid sequence of the Mn-Lipoxygenase precursor (618 amino acids, 67.

8p system191 01-06-2013 37 4   Download

The Arabidopsis FAE1 b-ketoacyl-CoA synthase (FAE1 KCS) catalyzes the condensation of malonyl-CoA with longchain acyl-CoAs. Sequence analysis of FAE1 KCS predicted that this condensing enzyme is anchored to a membrane by two adjacent N-terminal membrane-spanning domains. In order to characterize the FAE1 KCS and analyze its mechanism, FAE1 KCS and its mutants were engineered with a His6-tag at their N-terminus, and expressed in Saccharomyces cerevisiae. The membrane-bound enzyme was then solubilized and purified to near homogeneity on a metal affinity column.

9p research12 01-06-2013 46 3   Download

Cloning and over-expression of human glucose 6-phosphate dehydrogenase (Glc6P dehydrogenase) has for the first time allowed a detailed kinetic study of a preparation that is genetically homogeneous and in which all the protein molecules are of identical age. The steady-state kinetics of the recombinant enzyme, studied by fluorimetric initial-rate measurements, gave converging linear Lineweaver–Burk plots as expected for a ternary-complex mechanism.

8p research12 01-06-2013 66 4   Download

Strictosidine glucosidase (SG) is an enzyme that catalyses the second step in the biosynthesis of various classes of monoterpenoid indole alkaloids. Based on the comparison of cDNA sequences of SG from Catharanthus roseus and raucaffricine glucosidase (RG) from Rauvolfia serpentina, primers for RT-PCR were designed and the cDNA encoding SG was cloned from R. serpentina cell suspension cultures. The active enzyme was expressed in Escherichia coli and purified to homogeneity. Analysis of its deduced amino-acid sequence assigned the SG from R. serpentina to family 1 of glycosyl hydrolases.

10p research12 01-06-2013 46 5   Download

Mitochondrial DNA (mtDNA) deletion mutations accumulate with age in tissues of a variety of species. Although the relatively low calculated abundance of these deletion mutations in whole tissue homogenates led some investigators to suggest that these mutations do not have any physiological impact, their focal and segmental accumulation suggests that they can, and do, accumulate to levels sufficient to affect the metabolism of a tissue.

6p research12 01-06-2013 25 4   Download

A cDNA encoding 6-phosphofructo-2-kinase/fructose-2,6bisphosphatase was isolated from a Spinacia oleracea leaf library and used to express a recombinant enzyme in Escherichia coli and Spodoptera frugiperda cells. The insoluble protein expressed in E. coli was purified and used to raise antibodies. Western blot analysis of a protein extract from spinach leaf showed a single band of 90.8 kDa. Soluble protein was purified to homogeneity from S. frugiperda cells infected with recombinant baculovirus harboring the isolated cDNA. ...

11p research12 01-06-2013 43 5   Download

The present study reports the first purification and kinetic characterization of two plant arogenate dehydrogenases (EC 1.3.1.43), an enzyme that catalyses the oxidative decarboxylation of arogenate into tyrosine in presence of NADP. The twoArabidopsis thalianaarogenate dehy-drogenases TyrAAT1 and TyrAAT2 were overproduced in Escherichia coliand purified to homogeneity. Bio-chemical comparison of the two forms revealed that at low substrate concentration TyrAAT1 is four times more efficient in catalyzing the arogenate dehydrogenase reac-tion than TyrAAT2. ...

9p research12 23-04-2013 50 4   Download

Recombinant glycerol dehydratase ofKlebsiella pneumoniae was purified to homogeneity. The subunit composition of the enzyme was most probablya2b2c2 .When(R)- and (S)-propane-1,2-diolswere used independently as substrates, the rate with the (R)-enantiomer was 2.5 times faster than that with the (S)-isomer. In contrast to diol dehydratase,an iso-functional enzyme,the affinity of the enzyme for the (S)-isomer was essentially the same or only slightly higher than that for the (R)-isomer (Km(R) /Km(S) ¼1.5). ...

11p research12 23-04-2013 36 2   Download

The nitrilase AtNIT1 fromArabidopsis thalianawas over-expressed inEscherichia coliwith an N-terminal His6tag and puri®ed by zinc chelate anity chromatography in a single step almost to homogeneity in a 68% yield with a speci®c activity of 34.1 Uámg )1 . The native enzyme (450 kDa) consists of 11±13 subunits (38 kDa). The temperature optimum was determined to be 35°C, and a pH optimum of 9 was found.

8p research12 23-04-2013 28 3   Download

In this article, we report the results of an analysis of the glycolytic enzyme enolase (2-phospho-D-glycerate hydro-lase) of Trypanosoma brucei. Enolase activity was detected in both bloodstream-form and procyclic insect-stage try-panosomes, although a 4.5-fold lower specific activity was found in the cultured procyclic homogenate. Subcellular localization analysis showed that the enzyme is only pre-sent in the cytosol.

9p tumor12 20-04-2013 30 3   Download

Strains ofPseudomonas syringaepv. porri are characterized by a number of pathovar-specific phenotypic and genomic characters and constitute a highly homogeneous group. Using monoclonal antibodies, they all were classified in a novelP. syringaeserogroup O9. The O polysaccharides (OPS) isolated from the lipopolysaccharides (LPS) of P. syringaepv.

8p tumor12 20-04-2013 38 3   Download

Theuppgene, encoding uracil phosphoribosyltransferase (UPRTase) from the thermoacidophilic archaeon Sulfolobus solfataricus, was cloned and expressed inEscherichia coli. The enzyme was purified to homogeneity. It behaved as a tetramer in solution and showed optimal activity at pH 5.5 when assayed at 60
C. Enzyme activity was strongly stimulated by GTP and inhibited by CTP.

14p awards 06-04-2013 24 5   Download

We have cloned NADH oxidase homologues fromPyrococcus horikoshii and P. furiosus, and purified the recombinant form of the P. horikoshii enzyme to homogeneity from Escherichia coli. Both enzymes (previously referred to as NOX2) have been shown to act as a coenzyme A disulfide reductases (CoADR: CoA-S-S-CoA + NAD(P)H + H +fi2CoA-SH + NAD(P) + ). The P. horikoshiienzyme shows a kcat app of 7.2 s )1 with NADPH at 75
C.

0p awards 06-04-2013 39 4   Download

The extremely heat-stable 5¢-methylthioadenosine phos-phorylase from the hyperthermophilic archaeonPyrococcus furiosuswas cloned, expressed to high levels inEscherichia coli, and purified to homogeneity by heat precipitation and affinity chromatography. The recombinant enzyme was subjected to a kinetic analysis including initial velocity and product inhibition studies. The reaction follows an ordered Bi–Bi mechanism and phosphate binding precedes nucleo-side binding in the phosphorolytic direction....

11p awards 05-04-2013 40 2   Download

Bifidobacteriumbifidumis a useful probiotic agent exhibiting health-promoting properties and containsD-aspartate as an essential component of the cross-linker moiety in the pepti-doglycan. To help understandD-aspartate biosynthesis in B. bifidumNBRC 14252, aspartate racemase, which cata-lyzes the racemization ofD-andL-aspartate, was purified to homogeneity and characterized. The enzyme was a mono-mer with amolecularmass of 27 kDa. This is the first report showing the presence of a monomeric aspartate racemase....

0p awards 05-04-2013 43 2   Download

The regulation of adenosine kinase (AK) activity has the potential to control intracellular and interstitial adenosine (Ado) concentrations. In an effort to study the role of AK in Ado homeostasis in the central nervous system, two iso-forms of the enzymewere cloned fromamouse brain cDNA library. Following overexpression in bacterial cells, the cor-responding proteins were purified to homogeneity.

9p awards 05-04-2013 42 3   Download

In order to perform biochemical and pharmacological characterization of CXCR1, we designed several CXCR1 constructs. All constructs, including a CXCR1–Gi2a fusion protein, were produced in insect cells after infection with recombinant baculovirus. The recombinant receptors exhibited specific high-affinity binding of 125 I-labelled interleukin-8, and Scatchard transformation of the binding data indicated the presence of a population of single homogenous binding sites.

13p dell39 03-04-2013 34 2   Download