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PubMed2002

Survivin as a cell cycle-related and antiapoptotic protein in granulosa cells.

Survivin is a relatively unique member of the inhibitor of apoptosis protein (IAP) family in that it contains a single baculovirus IAP repeat (BIR) domain combined with a COOH-terminal alpha-helix coiled-coil domain instead of the more common zinc-binding RING finger. Results from a variety of transformed or continuous mammalian cell lines suggest that, due to the combination of these features, Survivin is capable of regulating both cell proliferation and apoptotic cell death. However, to date there is essentially no information regarding Survivin expression, regulation or function within the ovary, or in any nonmammalian vertebrate species. In the present studies, cDNAs for chicken (ch) Survivin-142 (homologous to human Survivin-142) plus three alternatively spliced variants (ch Survivin-short, -gamma, and -delta) are described, and of these, transcripts for ch Survivin-142 and -short are expressed in granulosa cells from the hen ovary. Highest levels of Survivin mRNA during follicle development occur in mitotically active granulosa cells from undifferentiated, prehierarchal follicles. Cell cycle analysis determined that Survivin mRNA expression is elevated specifically during the G2/M phase of mitosis. Significantly, transient transfection with ch Survivin-142 in primary cultures of hen granulosa cells attenuates taxol- and N-octanoylsphingosine- (C8-ceramide-) induced caspase-3 activity, whereas overexpression of ch Survivin-short (a truncated variant that lacks much of the functional BIR domain plus the entire alpha-helix coil domain) lacks this antiapoptotic activity. Taken together, these data provide evidence for Survivin in granulosa cells acting as a bifunctional protein associated with regulation of the cell cycle and the inhibition of apoptosis.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2002

Redox properties of rubredoxin variants as a function of solvent composition and temperature: investigation of monopolar and dipolar interactions.

The role of solvent composition and temperature on equilibrium electron transfer in seven rubredoxin variants [ Clostridium pasteurianum ( Cp), V8D, V8R, V8A, V44A Cp, Pyrococcus furiosus ( Pf), and A44V Pf] were investigated to examine the role of both monopolar and dipolar interactions. The reduction potentials of all variants decreased as the polarity of the solvent decreased. The enthalpy and entropy associated with electron transfer were determined from temperature-controlled voltammetric studies. The entropic contribution [delta( Tdelta S degrees )] to the change in the reduction potential was larger for charged variants (V8D and V8R), while the enthalpic contribution [delta(-delta H degrees )] was larger for the other mutants. The large entropy change observed for monopolar variants is likely due to solvent reorganization that occurs between oxidation states. Entropic-enthalpic compensation phenomena, an observation that most proteins have an entropic term [delta( Tdelta S degrees )] and enthalpic term [delta(-delta H degrees )] with opposite signs, was observed. A correlation of the size of the amino acid side chain with delta E degrees ', delta(-delta H degrees ), and delta( Tdelta S degrees ) is also discussed.

Bacterial Proteins↗
PubMed1988

Isoelectric focusing in immobilized pH gradients with carrier ampholytes added for high-resolution phenotyping of bovine beta-lactoglobulins: characterization of a new genetic variant.

The genetic variants of bovine beta-lactoglobulin (beta-lg) from the "Murnau-Werdenfelser" breed were analyzed in three different isoelectric focusing (IEF) systems. While carrier ampholyte IEF with a pH gradient of 0.2 pH/cm did not resolve the new variant W from the B variant and IEF in immobobilized pH gradients (IPG) with 0.1 pH/cm only partially resolved it, adequate separation was achieved with IPG-IEF in a pH 5.25-pH 5.7 gradient, in presence of 0.8 % w/v carrier ampholytes, both over a 10 and 17 cm separation distance. Apparent isoelectric points (pI's) and genetic frequencies (f) were as follows: beta-lg A, pI = 5.370, f = 0.364; beta-lg B, pI = 5.485, f = 0.480; beta-lg W, pI = 5.492, f = 0.076; and beta-lg D, pI = 5.610, f = 0.080. The small difference of delta pI = 0.007 between beta-lg B and beta-lg W respectively, seems to originate from a "silent" substitution of neutral amino acid residues as compared to the larger delta pI's of the other genetic variants of beta-lg, which result from substitution of charged amino acids.

Animals↗
PubMed2001

Transcriptional activities of p73 splicing variants are regulated by inter-variant association.

p73 has been identified as a gene that encodes a protein with significant identity with the tumour suppressor p53. The main structural difference between p73 and p53 is the additional C-terminal region of p73. Six isoforms of p73 with differing C-terminal structures, alpha, beta, gamma, delta, epsilon and xi, have been reported. These variants differ in transcriptional activity on p53-responsive promoters. Here we report a possible mechanism of transcriptional activation by p73 splicing variants. C-terminal deletion mutants of p73 alpha showed a significantly higher level of transcriptional activity than wild-type p73 alpha, suggesting that the C-terminal structure of p73 alpha functions to repress the transcriptional activity of p73 alpha. The results of immunoprecipitation assays and two-hybrid assays in mammalian cells showed that the p73 variants interacted with each other, but not with p53. The transcriptional activity of p73 beta was reduced by co-expression with either p73 alpha or p73 epsilon, which bears an identical C-terminal structure to p73 alpha. Co-expression of the C-terminal portion of p73 alpha or p73 epsilon with p73 beta also resulted in reduced transcriptional activity. Moreover, we observed that the level of endogenous p21 protein induced by p73 beta was decreased by co-expression of full-length p73 epsilon or the C-terminal region of p73 alpha or p73 epsilon. These observations suggest that p73-mediated gene expression is regulated by the interactions of p73 splicing variants in the cell.

Animals↗
PubMed1993

The structure and function of normal and abnormal haemoglobins.

This chapter reviews general aspects of the normal human haemoglobins which include those predominantly present in the embryo, the fetus and newborn baby, and in the normal adult. Special emphasis is given to factors which affect the levels of fetal haemoglobin in the adult because increased percentages of Hb F can be of great benefit to adults with certain haemoglobinopathies such as sickle cell anaemia and beta-thalassaemia. A review of the numerous Hb variants published since the discovery of Hb S in 1959 reveals a steady stream of newly detected abnormalities; most of these are the result of single-point mutations in the alpha-, beta-, gamma-, or delta-globin genes. Of the more than 600 variants listed in a repository, some 200 have clinical significance because of a decreased stability, a change in functional properties, among others. Methodology developed for the detection and quantitation of normal and abnormal Hb components has been greatly modified during the past 30 years; isoelectrofocusing and different fast developing micro chromatographic procedures are the methods of choice. Analyses of DNA isolated from the white cells has become most useful for the final characterization of the variants; this methodology consists of amplification of a desired segment of DNA and identification of a mutation with labelled oligonucleotide probes. Additional methods include sequence determination of this amplified DNA and identification of known mutations with an allele specific amplification procedure.

Adult↗
PubMed1990

Expression and function of gamma delta- and alpha beta-T cell receptor heterodimers on human somatic T cell hybrids.

T cell somatic hybrids were obtained by fusion of human tetanus toxoid-specific gamma + delta + T cells and a T cell lymphoma cell line that expresses beta-chain but not alpha-chain transcripts. The hybrids simultaneously and independently expressed alpha beta and gamma delta TCR heterodimers on the cell surface without any significant differences in the level of expression. No heterodimers containing alpha delta-, beta delta-, beta gamma-, and alpha gamma-chains were transported to the cell membrane, indicating a chain specificity in dimer formation. The presence of productively rearranged gamma- and delta-alleles in the hybrid cells and immunoprecipitation of an identical type of TCR-gamma delta from both hybrid and parental gamma + delta + T cells suggests that TCR-gamma delta on the hybrid cells derives from gamma + delta + T cells. Anti-TCR (TCS-delta 1 or WT31) and anti-CD3 antibodies induced a rapid increase in [Ca2+]i in the double-positive hybrids and their variants positive for either the alpha beta or gamma delta complex. Double positive hybrid cells were refractory to stimulation with anti-CD3 antibody after pretreatment with a mixture of anti-TCR-gamma delta and anti-TCR-alpha beta antibodies but not with either antibody alone indicating the functional independence of the two receptors. However, only gamma delta heterodimer receptor was able to respond to tetanus toxoid presented on autologous APC as measured by induction of the p55 chain of IL-2R on stimulated cells.

Alleles↗
PubMed2004

Effect of genetic variation on the thermal stability of human serum albumin.

Reversible thermal denaturation of 33 genetic variants of human serum albumin (HSA) appeared to be a two-state process when studied by circular dichroism (CD). Fourteen single-residue variants have Tm values (midpoint of denaturation) higher than, and nine have Tm values lower than, their endogenous, wild-type counterpart. Nine single-residue variants have DeltaHv values (van't Hoff enthalpy) higher than, and 14 have DeltaHv values lower than, normal albumin. All types of combinations of positive and negative DeltaTm values and Delta(DeltaHv) values were found. Good linear correlations between mutation-induced changes of alpha-helical content and Delta(DeltaHv) values, but not DeltaTm values, were found especially for the variants mutated in domains I and III. The effect of altered chain length and glycosylation on Tm and DeltaHv was also studied. For all variants, no clear relationship was found between the changes in the thermodynamic parameters and the type of substitution, changes in protein charge or hydrophobicity. However, the protein changes taking place in domain I have a rather uniform effect (almost all of the nine variants have positive DeltaTm values and negative Delta(DeltaHv) values, i.e., they denature more easily than normal albumin but they do so at a higher temperature). The present results can be of both protein chemical relevance and of clinical interest, because they could be useful when designing stable, recombinant HSAs for clinical applications.

Circular Dichroism↗
PubMed2006

Rin1 regulates insulin receptor signal transduction pathways.

Rin1 is a multifunctional protein containing several domains, including Ras binding and Rab5 GEF domains. The role of Rin1 in insulin receptor internalization and signaling was examined by expressing Rin1 and deletion mutants in cells utilizing a retrovirus system. Here, we show that insulin-receptor-mediated endocystosis and fluid phase insulin-stimulated endocytosis are enhanced in cells expressing the Rin1:wild type and the Rin1:C deletion mutant, which contain both the Rab5-GEF and GTP-bound Ras binding domains. However, the Rin1:N deletion mutant, which contains both the SH2 and proline-rich domains, blocked insulin-stimulated receptor-mediated and insulin-stimulated fluid phase endocytosis. In addition, the expression of Rin1:delta (429-490), a natural occurring splice variant, also blocked both receptor-mediated and fluid phase endocystosis. Furthermore, association of the Rin1 SH2 domain with the insulin receptor was dependent on tyrosine phosphorylation of the insulin receptor. Morphological analysis indicates that Rin1 co-localizes with insulin receptor both at the cell surface and in endosomes upon insulin stimulation. Interestingly, the expression of Rin1:wild type and both deletion mutants blocks the activation of Erk1/2 and Akt1 kinase activities without affecting either JN or p38 kinase activities. DNA synthesis and Elk-1 activation are also altered by the expression of Rin1:wild type and the Rin1:C deletion mutant. In contrast, the expression of Rin1:delta stimulates both Erk1/2 and Akt1 activation, DNA synthesis and Elk-1 activation. These results demonstrate that Rin1 plays an important role in both insulin receptor membrane trafficking and signaling.

Cell Line↗
PubMed2003

The p54 cleaved form of the tyrosine kinase Lyn generated by caspases during BCR-induced cell death in B lymphoma acts as a negative regulator of apoptosis.

Engagement of the B cell receptor antigen (BCR) triggers apoptosis on immature B cell lines. We report here that BCR triggering leads to caspase activation followed by Lyn cleavage and induction of apoptosis. The cleavage process is mitochondrion-dependent and involves caspases 9 and 7. Stable expression of the cleaved form of Lyn (Lyn-Delta-N) in Ramos B cells impairs BCR-mediated apoptosis as judged by loss of Delta(psi)m, caspase activation and PARP cleavage. Activation of the main survival pathways upon BCR-triggering was unaltered in both cell variants. However, the PI3-K inhibitor Ly294002 resensitizes Lyn-Delta-N cells to apoptosis. Selected cDNA expression arrays revealed that anti-IgM modulates the expression of approximately 20 genes in both cell variants. Among them, only c-Myc was found to be differentially regulated, which suggests a role for c-Myc in the B cell apoptotic response. Interestingly, c-Myc expression decreased more rapidly in Lyn-Delta-N compared with Lyn-WT cells during the first hours of anti-IgM stimulation. Nevertheless, rapid down-regulation of c-Myc following BCR engagement seems to correlate with the resistance of B cells to apoptosis. Thus, the soluble form of Lyn generated by caspases following BCR triggering acts as an inhibitor of B lymphocyte death likely through the modulation of c-Myc expression.

Apoptosis↗
PubMed1995

Characterization of a recombinant antihaemophilia-A factor (factor VIII-delta II) by matrix-assisted laser desorption/ionization mass spectrometry.

Factor VIII-delta II is a genetically engineered deletion variant of factor VIII, expressed by recombinant Chinese hamster ovary cells. This 1436-residues-long protein has a molecular mass, calculated from its sequence, of 164,954 Da and exhibits seven potential glycosylation sites. The glycoprotein, secreted as a single polypeptide chain, can be cleaved after Arg740 to generate a heavy-light chain complex of 90-80 kDa as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Due to its high mass range and excellent sensitivity, matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) has been chosen to play a key role in the precise determination of the molecular masses of recombinant factor VIII and the localization of the post-translational modifications within the protein. Native factor VIII-delta II displays a molecular mass of 178 kDa. The masses measured by MALDI for the heavy and light chains are respectively 89,900 Da and 87,100 Da. These mass values, found reproducible from batch to batch, are used to characterize factor VIII-delta II during the course of preclinical studies. The difference from the theoretical molecular molecular masses and the observation of broad molecular peaks suggest that recombinant FVIII-delta II has been effectively glycosylated by the host cell on both heavy and light chains. Similarly to plasma-derived factor VIII, the recombinant protein is proteolyzed by thrombin to generate the A1/A2/A3-C1-C2 trimer that is the active form of factor VIII in the coagulation pathway. MALDI-MS analysis of activated factor VIII-delta II suggested the presence of N-linked oligosaccharides in the proteolyzed light chain (A3-C1-C2 of 77,750 Da) and in the A1 domain (46,400 Da) of the heavy chain. By contrast, the similarity between the experimental and theoretical masses of the A2 domain indicated that its single potential glycosylation site has not been utilized.

Enzyme Activation↗
PubMed2004

Mice lacking leukocyte common antigen-related (LAR) protein tyrosine phosphatase domains demonstrate spatial learning impairment in the two-trial water maze and hyperactivity in multiple behavioural tests.

Leukocyte common antigen-related (LAR) protein is a cell adhesion molecule-like receptor-type protein tyrosine phosphatase. We previously reported that in LAR tyrosine phosphatase-deficient (LAR-Delta P) mice the number and size of basal forebrain cholinergic neurons as well as their innervation of the hippocampal area was reduced. With the hippocampus being implicated in behavioural activity aspects, including learning and memory processes, we assessed possible phenotypic consequences of LAR phosphatase deficiency using a battery of rodent behaviour tests. Motor function and co-ordination tests as well as spatial learning ability assays did not reveal any performance differences between wildtype and LAR-Delta P mice. A spatial learning impairment was found in the difficult variant of the Morris water maze. Exploration, nestbuilding and activity tests indicated that LAR-Delta P mice were more active than wildtype littermates. The observed hyperactivity in LAR-Delta P mice could not be explained by altered anxiety or curiosity levels, and was found to be persistent throughout the nocturnal period. In conclusion, behavioural testing of the LAR-Delta P mice revealed a spatial learning impairment and a significant increase in activity.

Animals↗
PubMed2005

CaMK-II oligomerization potential determined using CFP/YFP FRET.

Members of the Ca(2+)/calmodulin-dependent protein kinase II (CaMK-II) family are encoded throughout the animal kingdom by up to four genes (alpha, beta, gamma, and delta). Over three dozen known CaMK-II splice variants assemble into approximately 12-subunit oligomers with catalytic domains facing out from a central core. In this study, the catalytic domain of alpha, beta, and delta CaMK-IIs was replaced with cyan (CFP) or yellow fluorescent protein (YFP) for fluorescence resonance energy transfer (FRET) studies. FRET, when normalized to total CFP and YFP, reproducibly yielded values which reflected oligomerization preference, inter-subunit spacing, and localization. FRET occurred when individual CFP and YFP-linked CaMK-IIs were co-expressed, but not when they were expressed separately and then mixed. All hetero-oligomers exhibited FRET values that were averages of their homo-oligomeric parents, indicating no oligomeric preference or restriction. FRET for CaMK-II homo-oligomers was inversely proportional to the variable region length. FPs were monomerized (Leu221 to Lys221) for this study, thus eliminating any potential artifact caused by FP-CaMK-II aggregates. Our results indicate that alpha, beta, and delta CaMK-IIs can freely hetero-oligomerize and that increased variable region lengths place amino termini further apart, potentially influencing the rate of inter-subunit autophosphorylation.

Amino Acid Sequence↗
PubMed2004

Regulation of CCK-induced amylase release by PKC-delta in rat pancreatic acinar cells.

PKC is known to be activated by pancreatic secretagogues such as CCK and carbachol and to participate along with calcium in amylase release. Four PKC isoforms, alpha, delta, epsilon, and zeta, have been identified in acinar cells, but which isoforms participate in amylase release are unknown. To identify the responsible isoforms, we used translocation assays, chemical inhibitors, and overexpression of individual isoforms and their dominant-negative variants by means of adenoviral vectors. CCK stimulation caused translocation of PKC-alpha, -delta, and -epsilon, but not -zeta from soluble to membrane fraction. CCK-induced amylase release was inhibited approximately 30% by GF109203X, a broad spectrum PKC inhibitor, and by rottlerin, a PKC-delta inhibitor, but not by Gö6976, a PKC-alpha inhibitor, at concentrations from 1 to 5 microM. Neither overexpression of wild-type or dominant-negative PKC-alpha affected CCK-induced amylase release. Overexpression of PKC-delta and -epsilon enhanced amylase release, whereas only dominant-negative PKC-delta inhibited amylase release by 25%. PKC-delta overexpression increased amylase release at all concentrations of CCK, but dominant-negative PKC-delta only inhibited the maximal concentration; both similarly affected carbachol and JMV-180-induced amylase release. Overexpression of both PKC-delta and its dominant-negative variant affected the late but not the early phase of amylase release. GF109203X totally blocked the enhancement of amylase release by PKC-delta but had no further effect in the presence of dominant-negative PKC-delta. These results indicate that PKC-delta is the PKC isoform involved with amylase secretion.

Acetophenones↗
PubMed1998

Characterization of cucumber mosaic virus. VI. Generation of deletions in defective RNA 3s during passage in transgenic tobacco expressing the 3a gene.

Defective mutants of cucumber mosaic virus (CMV) RNA 3, containing deletions in the 3a gene were passaged in transgenic tobacco plants expressing the CMV 3a gene. After six passages, the various progeny RNA 3 were characterized. In all but one case, the size of the deletion increased. For the NheI-fs RNA 3 mutant of the Fny-strain of CMV (with an 8 nucleotide deletion), the deletion increased in the progeny viral RNA 3 to 570 nucleotides. For a similar frameshift mutant in RNA 3 of the M strain of CMV, either single RNA 3 species (with deletions of 579 or 627 nucleotides) or mixtures of RNA 3 deletion variants were observed in different plants. The DeltaE-H mutant (with a deletion of 202 nucleotides) of Fny-CMV RNA 3 underwent further deletion resulting in the loss of the entire 3a gene and flanking sequences. The DeltaKpnI mutant (deletion of 501 nucleotides) of Fny-CMV RNA 3 underwent a further deletion of 30 nucleotides. Except for the deletion progeny of the DeltaE-H RNA 3 mutant, the other defective RNA 3s all contained inframe deletions. It is proposed that the various deletions were created by different types of recombination and that packaging may be an important factor in the selection of particular defective RNA 3 variants.

Base Sequence↗
PubMed1993

Production of crystallizable cruzain, the major cysteine protease from Trypanosoma cruzi.

The major cysteine protease of Trypanosoma cruzi, cruzain, has been previously expressed in Escherichia coli as a fusion polypeptide. The proteolytic processing events required to obtain active, mature cruzain from the recombinant expression system have been characterized using mutational analysis of the cloned gene. An inactive variant of cruzain (cruzain-C25A) revealed that the proteolytic cleavage of the COOH-terminal domain from the recombinant cruzain is independent of cruzain activity. This cleavage event, presumably performed by another protease, was reduced, although not completely eliminated, in a variant in which the cleavage recognition site was altered (cruzain-E219P). To obtain a homogeneous COOH terminus of the recombinant enzyme, a truncated form of cruzain (cruzain-delta c) was engineered by insertion of a stop codon in the gene at a site corresponding to autoproteolysis observed with the native enzyme, purified from epimastigotes. Diffraction quality crystals of recombinant cruzain (cruzain) and the truncated variant (cruzain-delta c) have been produced and characterized. Cruzain and cruzain-delta c were cocrystallized with the peptide fluoromethyl ketone (FMK) inhibitors, Z-Phe-Arg-FMK and Z-Phe-Ala-FMK, respectively, (where Z is benzyloxycarbonyl). The crystals are monoclinic, space group P2(1), with a = 45.5 A, b = 51.0 A, c = 45.7 A, and beta = 116.1 degrees. One cruzain molecule is present in the asymmetric unit. The crystallographic data reveal that the high resolution structure determination is feasible. This system will facilitate the three-dimensional structure determinations and biochemical analyses of cruzain and cruzain variants.

Amino Acid Sequence↗
PubMed1994

The tyrosine corner: a feature of most Greek key beta-barrel proteins.

The Tyr corner is a conformation in which a tyrosine (residue "Y") near the beginning or end of an antiparallel beta-strand makes an H bond from its side-chain OH group to the backbone NH and/or CO of residue Y - 3, Y - 4, or Y - 5 in the nearby connection. The most common "classic" case is a delta 4 Tyr corner (more than 40 examples listed), in which the H bond is to residue Y - 4 and the Tyr chi 1 is near -60 degrees. Y - 2 is almost always a glycine, whose left-handed beta or very extended beta conformation helps the backbone curve around the Tyr ring. Residue Y - 3 is in polyproline II conformation (often Pro), and residue Y - 5 is usually a hydrophobic (often Leu) that packs next to the Tyr ring. The consensus sequence, then, is LxPGxY, where the first x (the H-bonding position) is hydrophilic. Residues Y and Y - 2 both form narrow pairs of beta-sheet H-bonds with the neighboring strand. delta 5 Tyr corners have a 1-residue insertion between the Gly and Tyr, forming a beta-bulge. One protein family has a delta 4 corner formed by a His rather than a Tyr, and several examples use Trp in place of Tyr. For almost all these cases, the protein or domain is a Greek key beta-barrel structure, the Tyr corner ends a Greek key connection, and it is well-conserved in related proteins. Most low-twist Greek key beta-barrels have 1 Tyr corner. "Reverse" delta 4 Tyr corners (H bonded to Y + 4) and other variants are described, all less common and less conserved. It seems likely that the more classic Tyr corners (delta 4, delta 5, and delta 3 Tyr, Trp, or His) contribute to the stability of a Greek key connection over a hairpin connection, and also that they may aid in the process of folding up Greek key structures.

Amino Acid Sequence↗
PubMed1992

Antigen binding thermodynamics and antiproliferative effects of chimeric and humanized anti-p185HER2 antibody Fab fragments.

The murine monoclonal antibody 4D5 (anti-p185HER2) inhibits the proliferation of human tumor cells overexpressing p185HER2 in vitro and has been "humanized" [Carter, P., Presta, L., Gorman, C. M., Ridgway, J. B. B., Henner, D., Wong, W.-L. T., Rowland, A. M., Kotts, C., Carver, M. E., & Shepard, H. M. (1992) Proc. Natl. Acad. Sci. U.S.A. (in press)] for use in human cancer therapy. We have determined the antigen binding thermodynamics and the antiproliferative activities of chimeric 4D5 Fab (ch4D5 Fab) fragment and a series of eight humanized Fab (hu4D5 Fab) fragments differing by amino acid substitutions in the framework regions of the variable domains. Fab fragments were expressed by secretion from Escherichia coli and purified from fermentation supernatants by using affinity chromatography on immobilized streptococcal protein G or staphylococcal protein A for ch4D5 and hu4D5, respectively. Circular dichroism spectroscopy indicates correct folding of the E. coli produced Fab, and scanning calorimetry shows a greater stability for hu4D5 (Tm = 82 degrees C) as compared with ch4D5 Fab (Tm = 72 degrees C). KD values for binding to the extracellular domain (ECD) of p185HER2 were determined by using a radioimmunoassay; the delta H and delta Cp for binding were determined by using isothermal titration calorimetry. ch4D5 Fab and one of the humanized variants (hu4D5-8 Fab) bind p185HER2-ECD with comparable affinity (delta G degrees = -13.6 kcal mol-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1981

Poly (delta-L-ornithine).

Poly (delta-L-Orn) is an example of an iso-polypeptide (i.e. variant of the usual poly a-peptide chain), where the a-carboxyl and delta-amino groups of ornithine are used in polymerization while the a-amino groups form the side chain. A procedure for the synthesis of this iso-polypeptide is described. Circular dichroism studies of poly (delta-L-Orn) and its Na-Boc derivative suggest that these polymers might adopt a conformation in solution similar to the beta-pleated sheet.

Circular Dichroism↗