The amino acid sequence of human chorionic gonadotropin. The alpha subunit and beta subunit.

The amino acid sequences of both the alpha and beta subunits of human chorionic gonadotropin have been determined. The amino acid sequence of the alpha subunit is: Ala - Asp - Val - Gln - Asp - Cys - Pro - Glu - Cys-10 - Thr - Leu - Gln - Asp - Pro - Phe - Ser - Gln-20 - Pro - Gly - Ala - Pro - Ile - Leu - Gln - Cys - Met - Gly-30 - Cys - Cys - Phe - Ser - Arg - Ala - Tyr - Pro - Thr - Pro-40 - Leu - Arg - Ser - Lys - Lys - Thr - Met - Leu - Val - Gln-50 - Lys - Asn - Val - Thr - Ser - Glu - Ser - Thr - Cys - Cys-60 - Val - Ala - Lys - Ser - Thr - Asn - Arg - Val - Thr - Val-70 - Met - Gly - Gly - Phe - Lys - Val - Glu - Asn - His - Thr-80 - Ala - Cys - His - Cys - Ser - Thr - Cys - Tyr - Tyr - His-90 - Lys - Ser. Oligosaccharide side chains are attached at residues 52 and 78. In the preparations studied approximately 10 and 30% of the chains lack the initial 2 and 3 NH2-terminal residues, respectively. This sequence is almost identical with that of human luteinizing hormone (Sairam, M. R., Papkoff, H., and Li, C. H. (1972) Biochem. Biophys. Res. Commun. 48, 530-537). The amino acid sequence of the beta subunit is: Ser - Lys - Glu - Pro - Leu - Arg - Pro - Arg - Cys - Arg-10 - Pro - Ile - Asn - Ala - Thr - Leu - Ala - Val - Glu - Lys-20 - Glu - Gly - Cys - Pro - Val - Cys - Ile - Thr - Val - Asn-30 - Thr - Thr - Ile - Cys - Ala - Gly - Tyr - Cys - Pro - Thr-40 - Met - Thr - Arg - Val - Leu - Gln - Gly - Val - Leu - Pro-50 - Ala - Leu - Pro - Gin - Val - Val - Cys - Asn - Tyr - Arg-60 - Asp - Val - Arg - Phe - Glu - Ser - Ile - Arg - Leu - Pro-70 - Gly - Cys - Pro - Arg - Gly - Val - Asn - Pro - Val - Val-80 - Ser - Tyr - Ala - Val - Ala - Leu - Ser - Cys - Gln - Cys-90 - Ala - Leu - Cys - Arg - Arg - Ser - Thr - Thr - Asp - Cys-100 - Gly - Gly - Pro - Lys - Asp - His - Pro - Leu - Thr - Cys-110 - Asp - Asp - Pro - Arg - Phe - Gln - Asp - Ser - Ser - Ser - Ser - Lys - Ala - Pro - Pro - Pro - Ser - Leu - Pro - Ser-130 - Pro - Ser - Arg - Leu - Pro - Gly - Pro - Ser - Asp - Thr-140 - Pro - Ile - Leu - Pro - Gln. Oligosaccharide side chains are found at residues 13, 30, 121, 127, 132, and 138. The proteolytic enzyme, thrombin, which appears to cleave a limited number of arginyl bonds, proved helpful in the determination of the beta sequence.     

The primary structure of the β-subunit of protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa

The complete amino acid sequence of the β-subunit of protocatechuate 3,4-dioxygenase was determined. The β-subunit contained four methionine residues. Thus, five peptides were obtained after cleavage of the carboxymethylated β-subunit with cyanogen bromide, and were isolated on Sephadex G-75 column chromatography. The amino acid sequences of the cyanogen bromide peptides were established by characterization of the peptides obtained after digestion with trypsin, chymotrypsin, thermolysin, or Staphylococcus aureus protease. The major sequencing techniques used were automated and manual Edman degradations. The five cyanogen bromide peptides were aligned by means of the amino acid sequences of the peptides containing methionine purified from the tryptic hydrolysate of the carboxymethylated β-subunit. The amino acid sequence of all the 238 residues was as follows: ProAlaGlnAspAsnSerArgPheValIleArgAsp ArgAsnTrpHis ProLysAlaLeuThrPro-Asp — TyrLysThrSerIleAlaArg SerProArgGlnAla LeuValSerIleProGlnSer — IleSerGluThrThrGly ProAsnPheSerHisLeu GlyPheGlyAlaHisAsp-His — AspLeuLeuLeuAsnPheAsn AsnGlyGlyLeu ProIleGlyGluArgIle-Ile — ValAlaGlyArgValValAsp GlnTyrGlyLysPro ValProAsnThrLeuValGluMet — TrpGlnAlaAsnAla GlyGlyArgTyrArg HisLysAsnAspArgTyrLeuAlaPro — LeuAspProAsn PheGlyGlyValGly ArgCysLeuThrAspSerAspGlyTyrTyr — SerPheArg ThrIleLysProGlyPro TyrProTrpArgAsnGlyProAsnAsp — TrpArgProAla HisIleHisPheGlyIle SerGlyProSerIleAlaThr-Lys — LeuIleThrGlnLeuTyr PheGluGlyAspPro LeuIleProMetCysProIleVal — LysSerIleAlaAsn ProGluAlaValGlnGln LeuIleAlaLysLeuAspMetAsnAsn — AlaAsnProMet AsnCysLeuAlaTyr ArgPheAspIleValLeuArgGlyGlnArgLysThrHis PheGluAsnCys. The sequence published earlier in summary form (Iwaki et al., 1979, J. Biochem.86, 1159–1162) contained a few errors which are pointed out in this paper.     

Tau and GSK3β Dephosphorylations are Required for Regulating Pin1 Phosphorylation

Pin1 binds mitotically phosphorylated Thr231–Pro232 and Thr212–Pro213 sites on tau, and a Pin1 deficiency in mice leads to tau hyperphosphorylation. The aim of this study was to determine if the dephosphorylation or inhibition of tau and GSK3β phosphorylation induces the Pin1 phosphorylation. To test this, human SK-N-MC cells were stably transfected with a fusion gene containing neuron-specific enolase (NSE)-controlled APPsw gene(NSE/APPsw), to induce Aβ-42. The stable transfectants were then transiently transfected with NSE/Splice, lacking human tau (NSE/Splice), or NSE/hTau, containing human tau, into the cells. The NSE/Splice- and NSE/hTau-cells were then treated with lithium. We concluded that (i) there was more C99-β APP accumulation than C83-βAPP in APPsw-tansfectant and thereby promoted Aβ-42 production in transfectants. (ii) the inhibition of tau and GSK3β phosphorylations correlated with increase in Pin1 activation in NSE/hTau- cells. Thus, these observations suggest that Pin1 might have an inhibitive role in phosphorylating tau and GSK3β for protecting against Alzheimer’s disease.     

Characterization of the <Emphasis Type="Italic">Pragia fontium</Emphasis> Lipopolysaccharides

Lipopolysaccharides (LPSs) of two strains Pragia fontium 97U116 and 27480 were isolated and characterized; they were close to those of other representatives of the family Enterobacteriaceae in fatty acid composition and contained, respectively, 3-hydroxytetradecanoic acid as the predominant component (45.8 and 45.1%), tetradecanoic (23.5 and 28.9%), hexadecanoic (12.6 and 7.9%), hexadecenoic (12.6 and 7.9%), and dodecanoic (4.9 and 4.2%) fatty acids. The O-specific polysaccharides consisted of linear penta- and tetrasaccharide repeating units: →2)-α-D-Galf-(1→3)-α-L-Rhap2Ac-(1→4)-α-D-GlcpNAc-(1→2)-α-L-Rhap-(1→3)-β-D-GlcpNAc-(1→ →4)-β-D-ManpNAc3NAcA-(1→2)-α-L-Rhap-(1→3)-β-L-Rhap-(1→4)-α-D-GlcpNAc-(1→ The LPSs of P. fontium 97U116 and 27480 were serologically active and belonged to different serogroups; they were less toxic than those of strain E. coli O55:B5, but more pyrogenic than the Pyrogenal preparation.     

Mutations in Intron 1 and Intron 22 Inversion Negative Haemophilia A Patients from Western India

Despite increased awareness and diagnostic facilities, 70–80% of the haemophilia A (HA) patients still remain undiagnosed in India. Very little data is available on prevalent mutations in HA from this country. We report fifty mutations in seventy one Indian HA patients, of which twenty were novel. Ten novel missense mutations [p.Leu11Pro (p.Leu-8Pro), p.Tyr155Ser (p.Tyr136Ser), p.Ile405Thr (p.Ile386Thr), p.Gly582Val (p.Gly563Val) p.Thr696Ile (p.Thr677Ile), p.Tyr737Cys (p.Tyr718Cys), p.Pro1999Arg (p.Pro1980Arg), p.Ser2082Thr (p.Ser2063Thr), p.Leu2197Trp (p.Leu2178Trp), p.Asp2317Glu (p.Asp2298Glu)] two nonsense [p.Lys396* (p.Lys377*), p.Ser2205* (p.Ser2186*)], one insertion [p.Glu1268_Asp1269ins (p.Glu1249_Asp1250)] and seven deletions [p.Leu882del (p.Leu863del), p.Met701del (p.Met682del), p.Leu1223del (p.Leu1204del), p.Trp1961_Tyr1962del (p.Trp1942_Tyr1943del) p.Glu1988del (p.Glu1969del), p.His1841del (p.His1822del), p.Ser2205del (p.Ser2186del)] were identified. Double mutations (p.Asp2317Glu; p.Thr696Ile) were observed in a moderate HA case. Mutations [p. Arg612Cys (p.Arg593Cys), p.Arg2326Gln (p.Arg2307Gln)] known to be predisposing to inhibitors to factor VIII (FVIII) were identified in two patients. 4.6% of the cases were found to be cross reacting material positive (CRM+ve). A wide heterogeneity in the nature of mutations was seen in the present study which has been successfully used for carrier detection and antenatal diagnosis in 10 families affected with severe to moderate HA.     

The Role of Phe181 in the Hexamerization of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Quinolinate Phosphoribosyltransferase

Quinolinic acid phosphoribosyltransferase (QAPRTase; NadC) catalyzes an indispensable step in NAD biosynthesis, one that is essential for cell survival in prokaryotes, which makes it an attractive target for antibacterial drug therapy. We recently reported the crystal structures of Helicobacter pylori QAPRTase with bound quinolinic acid, nicotinamide mononucleotide, and phthalic acid. The enzyme exists as a hexamer organized as a trimer of dimers, which is essential for full enzymatic activity. The loop between helix α7 and strand β8 contributes significantly to the hydrophobic dimer-dimer interactions. Phe181Pro mutation within the α7-β8 loop disrupts the hexamerization of QAPRTase, and the resultant dimer shows dramatically reduced protein stability and no activity. Our findings thus suggest that compounds able to disrupt its proper oligomerization could potentially function as selective inhibitors of Helicobacter pylori QAPRTase and represent a novel set of antibacterial agents.     

Identification of ligand binding site on RXRγ using molecular docking and dynamics methods

Retinoid X receptors (RXRα, β and γ) are recently known to be cancer chemotherapies targets. The ligand binding domains of RXRs have been crystallized, but the information of RXRγ ligand binding site is not yet available due to the lack of liganded complex. A thorough understanding of the ligand binding sites is essential to study RXRs and may result in cancer therapeutic breakthrough. Thus we aimed to study the RXRγ ligand binding site and find out the differences between the three subtypes. Alignment and molecular simulation were carried out for identifying the RXRγ ligand binding site, characterizing the RXRγ ligand binding mode and comparing the three RXRs. The result has indicated that the RXRγ ligand binding site is defined by helices H5, H10, β-sheet s1 and the end loop. Besides hydrophobic interactions, the ligand 9-cis retinoic acid interacts with RXRγ through a hydrogen bond with Ala106, a salt bridge with Arg95 and the π-π interactions with Phe217 and Phe218. The binding modes exhibit some similarities among RXRs, such as the interactions with Arg95 and Ala106. Nonetheless, owing to the absence of Ile47, Cys48, Ala50, Ala51 and residues 225∼237 in the active site, the binding pocket in RXRγ is two times larger than those of RXRα and RXRβ. Meanwhile, spatial effects of Trp84, Arg95, Ala106, Phe217 and Phe218 help to create a differently shaped binding pocket as compared to those of RXRα and RXRβ. Consequently, the ligand in RXRγ undergoes a “standing” posing which is distinct from the other two RXRs.     

Identification of novel functional variants of the melanocortin 1 receptor gene originated from Asians

Human melanocortin 1 receptor (MC1R) is a seven transmembrane G-coupled protein receptor that upregulates the cAMP pathway. Several functional variants of MC1R that show an impaired ability to activate the cAMP pathway are strongly associated with fair skin and red hair in Europeans and European descendants. The sequence variations of the MC1R gene were repeatedly investigated against worldwide populations; however, there was no evidence that functional variant of MC1R exists in non-European descendants. We report the presence of novel functional variants of MC1R with Asian origins. Three novel variants of MC1R, Phe147Δ, Thr157Ile, and Pro159Thr, were identified in our screening for the sequence variations of the MC1R gene against 995 individuals from 30 Asian and Oceanian populations; there was a single case for the Pro159Thr variant allele and two instances of Phe147Δ and Thr157Ile variant alleles. Our pharmacological assay revealed that Phe147Δ, Thr157Ile, and Pro159Thr variant showed similar or more dramatically impaired activities in comparison with Arg151Cys, which is a major functional variant of MC1R in Europeans. These functional variant alleles were geographically localized in relatively high latitudes, which suggest that the adaptation to ambient UV light intensity may play an important role in shaping the geographical distribution of MC1R alleles in Asia and Oceania.     

β-Carbon stereoselectivity of N-carbamoyl-d-α-amino acid amidohydrolase for α,β-diastereomeric amino acids

N-Carbamoyl-d-α-amino acid amidohydrolase (d-carbamoylase) was found to distinguish stereochemistry not only at the α-carbon but also at the β-carbon of N-carbamoyl-d-α-amino acids. The enzyme selectively acted on one of the four stereoisomers of N-carbamoyl-α,β-diastereomeric amino acids. This simultaneous recognition of two chiral centers by d-carbamoylase was useful for the fine stereoselective synthesis of α,β-diastereomeric amino acids such as threonine, isoleucine, 3,4-methylenedioxyphenylserine and β-methylphenylalanine. The stereoselectivity for the β-carbon was influenced by the pH of the reaction mixture and by the bulk of the substituent at the β-carbon. Received: 18 June 1999 / Received revision: 30 July 1999 / Accepted: 6 August 1999     

Flavonol glycosides in the leaves ofTrillium apetalon Makino andT. kamtschaticum pallas

Seven flavonol glycosides were isolated from the leaves ofT. apetalon. They were identified chromatographically and spectrally to be: quercetin/kaempferol 3-O-α-arabinopyranosyl-(1→6)-β-galactopyranoside (TQ and TK), quercetin/kaempferol 3-O-[2‴-O-acetyl-α-arabinopyranosyl]-(1→6)-β-galactopyranoside (TAQ and TAK), quercetin 3-O-β-glucoside (ISQ), isorhamnetin 3-O-α-arabinopyranosyl-(1→6)-β-galactopyranoside (TI) and isorhamnetin 3-O-[2‴-O-acetyl-α-arabinopyranosyl]-(1→6)-β-galactopyranoside (TAI). TQ, TAQ, TI and TAI were major constituents. This is the first report on two new isorhamnetin-type glycosides, TI and TAI. The seven flavonol glycosides identical to those ofT. apetalon were isolated and identified in the leaves ofT. kamtschaticum; TQ and TAQ were also major components, but TI and TAI were only minor components. TI and TAI were not detected in the leaves ofT. tschonoskii. These leaf-flavonoid patterns were discussed from a chemosystematic point of view. Part 3 in the series “Studies of the flavonoids of the genusTrillium”. For Part 2 see Yoshitamaet al., (1997) J. Plant Res.110: 379–381.     

SNPs in the porcine <Emphasis Type="Italic">PPARGC1a</Emphasis> gene: Interbreed differences and their phenotypic effects

Due to its function, the peroxisome proliferative activated receptor-γ, coactivator-1α (PPARGC1A) gene is a candidate in the search for genes that may affect production traits in the pig. The purpose of this study was to screen for new SNPs in exon 8 of the porcine PPARGC1A gene and to test their possible association with production traits. Altogether 736 pigs representing five breeds Polish Landrace, n=242; Polish Large White, n=192; Hampshire, n=27; Duroc, 21; Pietrain, n=12) and synthetic line 990 (n=242) were scanned via SSCP assay. Four SNPs were found; two new ones: C/G (His338Gln) and G/A Thr359Thr), and two previously reported ones: C/A (Arg369Arg) and T/A Cys430Ser). The missense T/A and C/G SNPs demonstrated pronounced interbreed variability in terms of allele frequencies, including the exclusive presence of the C/G substitution in the Hampshire breed. The tested SNPs occurred in five putative haplotypes, and their frequency also differed substantially between breeds. The association of the SNPs with production traits was tested for G/A (Thr359Thr), C/A (Arg369Arg) and T/A (Cys430Ser) substitutions in Polish Large White, Polish Landrace and line 990. The analysis revealed only breed-specific associations. The T/A (Cys430Ser) SNP was related to the feed conversion ratio in the Polish Large White (P=0.02), and the silent G/A and C/A substitutions were respectively associated with abdominal fat in line 990 and backfat thickness in Polish Landrace (P=0.04). The combined effects of the substitutions were estimated as haplotype effects. Three significant contrasts between haplotypes were calculated, but the observed associations were again only breed-specific.     

Effects of sulfur amino acids, <Emphasis Type="SmallCaps">l</Emphasis>-methionine, <Emphasis Type="SmallCaps">l</Emphasis>-cystine and <Emphasis Type="SmallCaps">l</Emphasis>-cysteine on lipoprotein lipase and hormone-sensitive lipase in differentiated mouse 3T3-L1 adipocytes

Rats subcutaneously implanted with AH109A hepatoma cells show hyperlipidemia with high concentrations of serum triglyceride and nonesterified fatty acid, suppression of lipoprotein lipase (LPL), and elevation of hormone-sensitive lipase (HSL) activities during the growth of the hepatoma. Supplementation of the diet with sulfur amino acids such as l-methionine (Met) and l-cystine (Cys) improved hyperlipidemia by restoring LPL and HSL activities. In the present study, we have attempted to examine the effects of sulfur amino acids on the activity and mRNA level of LPL and the activity of HSL using 3T3-L1 cells, which are known to differentiate to adipocytes. The adipocytes were incubated with various concentrations of Met, Cys or l-cysteine (CysH) in the absence or presence of tumor necrosis factor-α (TNF-α). LPL activity was suppressed by TNF-α. In the absence of TNF-α, Met, Cys and CysH did not change the LPL activity. In the presence of TNF-α, Met and Cys significantly increased the LPL activity, and Met also enhanced the LPL mRNA level. HSL activity was also suppressed by TNF-α. In the absence of TNF-α, Met enhanced the HSL activity. In the presence of TNF-α, Met, Cys and CysH suppressed the HSL activity. Sulfur amino acids such as Met, Cys and CysH affected the LPL activity, mRNA level, and HSL activity in 3T3-L1 adipocytes. Some of these effects of sulfur amino acids were different between LPL and HSL, between the absence and the presence of TNF-α, and between 3T3-L1 adipocytes and the adipose tissue from rats.     

A high risk phenotype of hypertrophic cardiomyopathy associated with a compound genotype of two mutated β-myosin heavy chain genes

Hypertrophic cardiomyopathy (HCM) is a genetically and clinically heterogeneous myocardial disease that is in most cases familial and transmitted in a dominant fashion. The most frequently affected gene codes for the cardiac (ventricular) β-myosin heavy chain. We have investigated the genetic cause of an isolated case of HCM, which was marked by an extremely severe phenotype and a very early age of onset. HCM is normally not a disease of small children. The proband was a boy who had suffered cardiac arrest at the age of 6.5years (resuscitation by cardioconversion). Upon screening of the β-myosin heavy chain gene as a candidate, two missense mutations, one in exon19 (Arg719Trp) and a second in exon12 (Met349Thr), were identified. The Arg719Trp mutation was de novo, as it was not found in the parents. In contrast, the Met349Thr mutation was inherited through the maternal grandmother. Six family members were carriers of this mutation but only the proband was clinically affected. Segregation and molecular analysis allowed us to assign the Met349Thr mutation to the maternal and the Arg719Trp de novo mutation to the paternal β-myosin allele. Thus, the patient has no normal myosin. We interpret these findings in terms of compound heterozygosity of a dominant (Arg719Trp) and a recessive (Met349Thr) mutation. Whereas a single mutated Arg719Trp allele would be sufficient to cause HCM, the concurrent Met349Thr mutation alone does not apparently induce the disease. Nevertheless, it conceivably contributes to the particularly severe phenotype. Received: 15 September 1997 / Accepted: 26 November 1997     

Adhesion forces in the self-recognition of oligosaccharide epitopes of the proteoglycan aggregation factor of the marine sponge <Emphasis Type="Italic">Microciona prolifera</Emphasis>

Cell aggregation in the marine sponge Microciona prolifera is mediated by a multimillion molecular-mass aggregation factor, termed MAF. Earlier investigations revealed that the cell aggregation activity of MAF depends on two functional domains: (i) a Ca²⁺-independent cell-binding domain and (ii) a Ca²⁺-dependent proteoglycan self-interaction domain. Structural analysis of involved carbohydrate fragments of the proteoglycan in the self-association established a sulfated disaccharide β-d-GlcpNAc3S-(1→3)-α-l-Fucp and a pyruvated trisaccharide β-d-Galp4,6(R)Pyr-(1→4)-β-d-GlcpNAc-(1→3)-α-l-Fucp. Recent UV, SPR, and TEM studies, using BSA conjugates and gold nanoparticles of the synthetic sulfated disaccharide, clearly demonstrated self-recognition on the disaccharide level in the presence of Ca²⁺-ions. To determine binding forces of the carbohydrate–carbohydrate interactions for both synthetic MAF oligosaccharides, atomic force microscopy (AFM) studies were carried out. It turned out that, in the presence of Ca²⁺-ions, the force required to separate the tip and sample coated with a self-assembling monolayer of thiol-spacer-containing β-d-GlcpNAc-(1→3)-α-l-Fucp-(1→O)(CH₂)₃S(CH₂)₆S- was found to be quantized in integer multiples of 30 ± 6 pN. No binding was observed between the two monolayers in the absence of Ca²⁺-ions. Cd²⁺-ions could partially induce the self-interaction. In contrast, similar AFM experiments with thiol-spacer-containing β-d-Galp4,6(R)Pyr-(1→4)-β-d-GlcpNAc-(1→3)-α-l-Fucp-(1→O)(CH₂)₃S(CH₂)₆S- did not show a binding in the presence of Ca²⁺-ions. Also TEM experiments of gold nanoparticles coated with the pyruvated trisaccharide could not make visible aggregation in the presence of Ca²⁺-ions. It is suggested that the self-interaction between the sulfated disaccharide fragments is stronger than that between the pyruvated trisaccharide.     

Structural elements of the C-terminal domain of subunit E (E<Subscript>133-222</Subscript>) from the <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> V<Subscript>1</Subscript>V<Subscript>O</Subscript> ATPase determined by solution NMR spectroscopy

Subunit E of the vacuolar ATPase (V-ATPase) contains an N-terminal extended α helix (Rishikesan et al. J Bioenerg Biomembr 43:187–193, 2011) and a globular C-terminal part that is predicted to consist of a mixture of α-helices and β-sheets (Grüber et al. Biochem Biophys Res Comm 298:383–391, 2002). Here we describe the production, purification and 2D structure of the C-terminal segment E_133-222 of subunit E from Saccharamyces cerevisiae V-ATPase in solution based on the secondary structure calculation from NMR spectroscopy studies. E_133-222 consists of four β-strands, formed by the amino acids from K136-V139, E170-V173, G186-V189, D195-E198 and two α-helices, composed of the residues from R144-A164 and T202-I218. The sheets and helices are arranged as β1:α1:β2:β3:β4:α2, which are connected by flexible loop regions. These new structural details of subunit E are discussed in the light of the structural arrangements of this subunit inside the V₁- and V₁V_O ATPase.     

Mass spectrometry of triterpene glycosides molecular complexation with purine bases of nucleic acids

For the first time, the molecular complexation of adenine and guanine with hederagenin 3-O-α-L-rhamnopyranosyl-(1 2)-O-α-L-arabinopyranoside (α-hederin) and its 28-O-α-L-rhamnopyranosyl-(1→4)-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl ester (hederasaponin C) was investigated using the method of electrospray ionization mass spectrometry. Guanine forms more diversely composed complexes than adenine.     

Effects of orally administrated amino acids on myofibrillar proteolysis in chicks

We examined the effects of orally administrated amino acids on myfibrillar proteolysis in food-deprived chicks. Plasma N(tau)-methylhistidine concentration, as an index of myofibrillar proteolysis, was decreased by the administration of Glu, Gly, Ala, Leu, Ile, Ser, Thr, Met, Trp, Asn, Gln, Pro, Lys and Arg but not by Asp, Val, Phe, Tyr or His to chicks. Orally administrated Cys was fatal to chicks. These results indicate that oral Glu, Gly, Ala, Leu, Ile, Ser, Thr, Met, Trp, Asn, Gln, Pro, Lys and Arg administration suppressed myofibrillar proteolysis in chicks.     

β-Amino acid residues: Conformational characterization of an N- and C-protected homo-β-(S)-leucine

Summary An N- and C-protected derivative ofhomo-β-leucine, Fmoc-homo-β-(S)-leucine methyl ester, synthesized from the corresponding proteinogenic parent α-amino acid in enantiopure form has been fully characterized in the solid state by X-ray diffraction analysis. The crystal conformation of this new residue indicates and extended conformation for thishomo-β-residue, with the ϕ torsion angle being more constrained than the μ and ψ angles.     

A critical evaluation of the conformational requirements of fusogenic peptides in membranes

It is generally assumed that fusogenic peptides would require a certain conformation, which triggers or participates in the rate-determining step of membrane fusion. Previous structure analyses of the viral fusion peptide from gp41 of HIV-1 have yielded contradictory results, showing either an α-helical or a β-stranded conformation under different conditions. To find out whether either of these conformations is relevant in the actual fusion process, we have placed sterically demanding substitutions into the fusion peptide FP23 to prevent or partially inhibit folding and self-assembly. A single substitution of either D- or L-CF₃-phenylglycine was introduced in different positions of the sequence, and the capability of these peptide analogues to fuse large unilamellar vesicles was monitored by lipid mixing and dynamic light scattering. If fusion proceeds via a β-stranded oligomer, then the D- and L-epimers are expected to differ systematically in their activity, since the D-epimers should be unable to form β-structures due to sterical hindrance. If an α-helical conformation is relevant for fusion, then the D-epimers would be slightly disfavoured compared to the L-forms, hence a small systematic difference in fusion activity should be observed. Interestingly, we find that (1) all D- and L-epimers are fusogenically active, though to different extents compared to the wild type, and – most importantly – (ii) there is no systematic preference for either the D- or L-forms. We therefore suggest that a well-structured α-helical peptide conformation or a β-stranded oligomeric assembly can be excluded as the rate-determining state. Instead, fusion appears to involve conformationally disordered peptides with a pronounced structural plasticity. Dedicated to Prof. K. Arnold on the occasion of this 65th birthday.