bluuebunny/crossref_metadata_2025_split huggingface dataset:
ISOLATION OF ANTITUMOR PROTEINS ABRIN‐A AND ABRIN‐B FROM ABRUS PRECATORIUS*
Authors: Lin Jung‐Yaw , Lee Te‐Chang , Tung Ta‐Cheng 
Published: August 2010

Two toxic proteins were purified from the seeds of Abrus precatorius by DEAE‐A 50 and Sepharose 4B chromatography. One of them does not bind on the Sepharose 4B column (Abrin‐b) and the other (Abrin‐a) is eluted with 0.2 M galactose. The amino acid compositions and tryptic maps of these two proteins were similar, but not identical. The molecular weights estimated by SDS‐gel electrophoresis were 67,000 for abrin‐b as compared with 65,000 for abrin‐a. In the presence of mercaptoethanol, both abrin‐a and abrin‐b gave rise to two bands.The lethal doses of abrin‐a and abrin‐b for mice recorded within 48 h were 10 and 25μg per kg of body weight respectively. Abrin‐a at 0.8 μg per ml concentration level agglutinated human 0‐type erythrocytes, whereas abrin‐b showed no such activity. Abrin‐a at 5 μg per ml concentration level agglutinated both the Sarcoma 180 cells and Ehrlich ascites tumor cells, but it required 150 μg per ml for abrin‐b. Both these two proteins at a sublethal dose could inhibit the growth of Ehrlich ascites tumor cells which were injected simultaneously with these proteins. 131I‐abrin‐a and 131I‐abrin‐b were able to bind Sarcoma 180 cells, and the binding of abrin‐a could be inhibited by lactose, raffinose, galactose and rhamnose, but none of 15 sugars tested inhibited the binding of abrin‐b.
ISOLATION AND PRIMARY STRUCTURE OF ADRENOCORTICOTROPIN FROM SEVERAL SPECIES OF WHALE
Authors: Kawauchi Hiroshi , Muramoto Koji , Ramachandran J. 
Published: August 2010

The isolation of adrenocorticotropin (ACTH) from fin (Balaenoptera physalus), sei (Blaenoptera borelis) and sperm (Physeter catodon) whale pituitaries is described.Their primary structures have been elucidated by the fluorescein isothiocyanate method and revealed to be identical to the structure of the human hormone. Fin whale exhibited an identical steroidogenic activity to that of the porcine hormone.
TRINITROPHENYLATION OF BOVINE GROWTH HORMONE
Authors: BONINO M.J. BISCOGLIO DE JIMENEZ , CASCONE O. , SANTOMÉ J.A. 
Published: August 2010

Bovine growth hormone was chemically modified with picryl sulfonic acid, at pH 8.4 during 2 and 5 min of reaction. The N‐terminal residue provides the most reactive amino group followed by the amino groups of lysine 179 and lysines 143, 69, 111, 170 and 166 in decreasing order.These results agree with those obtained previously with equine growth hormone, except that residue 156 is not modified in bovine growth hormone, An important decrease in biological activity occurs between 2 and 5 min of reaction without sensible modification in the α‐helix content of the molecule.
CYLIC PEPTIDES
Authors: YASUTAKE AKIRA , AOYAGI HARUHIKO , KATO TETSUO , IZUMIYA NOBUO 
Published: August 2010

Two diastereomeric cyclic tetrapeptides with a sequence of cyclo (‐D (and L)‐Tyr (Me)‐L‐Ile‐L‐Pro‐L‐Leu‐) (ID and IL) have been synthesized, which are simplified analogs of a phytotoxic peptide Cyl‐2, and contain an L‐proline and an L‐leucine residue in place of an L‐pipecolic acid and a 2‐amino‐8‐oxo‐9,10‐epoxydecanoic acid residue, respectively, in Cyl‐2. The cyclization of the H‐D‐Tyr(Me)‐L‐Ile‐L‐Pro‐L‐Leu‐ONSu proceeded smoothly to give ID in excellent yield (50%), but the cyclization of H‐L‐Tyr(Me)‐L‐Ile‐L‐Pro‐L‐Leu‐ONSu gave IL in much lower yield (10%).Based on the results of 1H‐ and 13C‐n.m.r. studies, differential N‐methylation and model buildings of ID, the backbone structure of ID has been proposed to be a unique trans‐trans‐cis‐trans conformation, the L‐Ile‐L‐Pro bond being cis.
OXIDATION OF TRYPTOPHAN TO OXINDOLYLALANINE BY DIMETHYL SULFOXIDE‐HYDROCHLORIC ACID
Authors: SAVIGE WALTER E. , FONTANA ANGELO 
Published: August 2010

Tryptophan is readily oxidized to oxindolylalanine (2‐hydroxytryptophan) in good yield on treatment in acetic acid solution with a mixture of dimethyl sulfoxide (DMSO) and concentrated aqueous HCl at room temperature. Other sulfoxides can be used in combination with HCl; for example, methionine sulfoxide reacts with an equimolar amount of tryptophan to give high yields of methionine and oxindolylalanine. Methionine and cysteine are quantitatively oxidized by DMSO/HCl to methionine sulfoxide and cystine, respectively.The tryptophan containing peptides LRF (luteinizing hormone‐releasing factor), somatostatin, valine‐gramicidin A and ACTH1–24were each treated with the DMSO/HCl reagent in acetic acid solution and the corresponding oxindolylalanine‐derivatives isolated in over 90% yield after chromatography. The identity and purity of the derivatives were established on the basis of ultraviolet spectral characteristics and quantitative amino acid analysis of the oxindolylalanine content of acid hydrolyzates of the oxidized peptides with 3N‐p‐toluenesulfonic acid at 110° for 24 h.The results indicate that modification of tryptophan peptides with DMSO/HCl provides a useful procedure, which seems superior to previously used reagents. In addition, the method could be well applied to other indoles of biological and pharmacological interest.
STUDIES ON THE COSUBSTRATE SITE OF PROTEASE SOLUBILIZED NADPH‐CYTOCHROME P450 REDUCTASE
Authors: LUMPER LUDWIG , BUSCH FRIEDHELM , DŽELIĆ ŠEHERAZADE , HENNING JÖRG , LAZAR TIBOR 
Published: August 2010

Modification of the protease solubilized NADPH‐cytochrome P450 reductase (= NADPH‐cytochrome c reductase) at the critical SH group in the cosubstrate binding site affects KNADPHm but not V for the cytochrome c reduction. The increase of KNADPHm is dependent on the size and the charge of the substituent introduced. Substitution of the cosubstrate site SH by the CN‐, S2 O3‐ and the (N‐ethyl) succinimido group effects a 3‐, 7‐ and 23‐fold increase of KNADPHm respectively. The critical SH group in the NADPH binding region can be specifically radiolabeled by N‐ethyl (2,3‐14C) maleimide after preincubation of the reductase with unlabeled NEM in the presence of 1 mM NADP+. The selective reaction at the essential cysteine in the cosubstrate site is demonstrated by peptide mapping of the thermolytic digest and urea SDS gel electrophoresis of the cyanogen bromide fragments of the reductase. Protease solubilized NADPH‐cytochrome P450 reductase is inactivated by reagents directed to histidine, orginine and lysine residues. NADP (H) (1 mM) and 2′‐AMP (1 mM) give effective protection only for the reaction of 1, 2‐cyclohexanedione (12 mM). The functional role of the basic amino acid residues for the cosubstrate binding by the NADPH‐cytochrome P450 reductase cannot be established therefore by the modification experiments described.The number of NADPH binding sites in the NADPH‐cytochrome P450 reductase is determined to one site/mol reductase by titration of the enzyme with NADP+ monitored by CD‐spectroscopy.
RIBONUCLEASE INHIBITOR FROM BOVINE BRAIN*
Authors: BURTON LOUIS E. , BLACKBURN PETER , MOORE STANFORD 
Published: August 2010

A ribonuclease inhibitor from bovine brain has been purified 27000‐fold by affinity chromatography on Sepharose‐RNase A with an overall yield of 46% (ca. 0.4 mg/kg tissue). The purified inhibitor gives a single band by SDS‐gel electrophoresis. By gel filtration the molecular weight is ca. 50 000; the molecular weight of the complex with bovine pancreatic RNase A is ca. 62 000, indicative of 1:1 binding on a molar basis. The inhibition of the action of RNase A on yeast RNA by the inhibitor is noncompetitive with a Kiof 7 times 10‐10 M. The protein is very similar in its properties, including amino acid composition, to the inhibitor previously isolated from human placenta. The amount of inhibitor per g of protein in bovine brain is about one‐seventh of the value for human placenta. No difference was found in the distribution of inhibitor between white and gray matter; one‐tenth of the inhibitor present is bound to a brain ribonuclease which is released in active form after reaction with p‐hydroxymercuribenzoate. Essentially no free neutral ribonuclease activity could be detected in brain homogenates in the absence of p‐hydroxymercuribenzoate.
PRIMARY STRUCTURE OF THE ACTIVE TRYPTIC FRAGMENTS OF HUMAN AND MONKEY SALIVARY ANIONIC PROLINE‐RICH PROTEINS
Authors: SCHLESINGER DAVID H. , HAY DONALD I. 
Published: August 2010

The primary structures of the four human salivary anionic proline‐rich proteins and an analogous protein from the saliva of a monkey (Macaca arctoides) have been further investigated. These proteins possess the unusual property of inhibiting crystal growth of calcium phosphate salts, and it has been proposed that they play an important role in the mouth, by preventing precipitation of calcium phosphate salts from the supersaturated saliva.The tryptic fragments responsible for this activity have been isolated from all five proteins and their complete amino acid sequences determined and compared. These active fragments have been unequivocally identified as the amino‐terminal segment in all five proteins. The structures of the four human fragments are identical except for the presence of Asn at residue 4 in PRP‐1 and ‐3 instead of Asp found in PRP‐2 and ‐4. Comparison of the 30 residue human fragments with the monkey fragment shows 18 residues to be identical in these peptides, providing that residue 1 of the monkey fragment is aligned with residue 3 of the human proteins.These studies constitute the next step in determining the mechanism of action of these unusual proteins, and in determining their minimum chain length required for inhibitory activity.
DIFFERENTIAL INHIBITION OF SERINE PROTEINASES BY RABBIT α 1‐PROTEINASE INHIBITORS F AND S
Authors: KOJ A. , REGOECZI E. 
Published: August 2010

Inhibition of six serine proteinases (bovine trypsin and chymotrypsin, equine leucocyte proteinases type 1 and 2A, porcine pancreatic elastase type III and rabbit plasmin) by rabbit α1‐proteinase inhibitors F and S was studied. In each case examined, the F form reacted more rapidly.The number of moles of an enzyme inhibited by one mole of α1 ‐proteinase inhibitor in a complete reaction (molar inhibitory capacity) ranged from 0.26 (leucocyte proteinase type 1) to 1.01 (trypsin). More significantly, however, the molar inhibitory capacities of both α1‐proteinase inhibitors differed for the same enzymes. The highest F/S inhibitory ratio was recorded with chymotrypsin (1.88), and the lowest with elastase (0.69). These differences in molar inhibitory capacities are likely to reflect the dual nature of the reaction between the inhibitor and a proteinase, that is, either complex formation or inactivation of α1‐proteinase inhibitor without enzyme inhibition.No evidence was obtained to suggest that differential reactivity and differential inhibitory capacity are interdependent. The observations are consistent with the view that rabbit α1‐proteinase inhibitors F and S are closely related yet functionally distinct proteins.
Peptide formation in the presence of metal ion protecting groups
Authors: ISIED STEPHAN S. , LYON JOHN , VASSILIAN ASBED 
Published: August 2010

A quantitative study of the degree of racemization induced by the [(NH3)5Co‐(III)‐] protecting group when bound to the C‐terminal of the amino acids Leu, Phe, and His, as has been carried out. Racemization was determined by forming the diastereomeric cobalt dipeptides [(Leu)(AA)Co(III)(NH3)5] where AA = L‐Leu, L‐Phe, and L‐His; after cobalt removal (using NaBH4), the peptide diastereomers were analyzed quantitatively using an amino acid analyzer. No racemization was observed within experimental error (0.3%) as a result of the substitution of the [(NH3)5Co(III)‐] group on the amino acids and peptides studied.
Marsupial hypothalamo‐neurohypophyseal hormones
Authors: HURPET DOMINIQUE , CHAUVET MARIE‐THERESE , CHAUVET JACQUELINE , ACHER ROGER 
Published: August 2010

The hypothalamo‐neurohypophyseal hormones of the brush‐tailed possum (Trichosurus vulpecula) have been purified through molecular sieving and paper chromatoelectrophoresis. Two peptides have been isolated, one with pressor property, the other with uterotonic activity. The pressor hormone has been identified as arginine vasopressin by amino acid composition and amino acid sequence. The oxytocin‐like hormone has been characterized as mesotocin by amino acid composition. The amounts per dried neuro‐intermediate gland (1.0–1.5 mg) are approximately 12 and 5 nmol, respectively.Up to now, mesotocin has only been found in non‐mammalian tetrapods, particularly in reptiles. Its preservation in Australian marsupials (Macropodidae and Phalangeridae), and the replacement of vasotocin by a vasopressin‐like peptide, suggests that they are transition species between reptiles and Eutheria. However, the presence of mesotocin raises the question of its role in marsupial lactation.
Reexamination of sodium‐liquid ammonia reduction in the peptide chemistry†
Authors: SCHON ISTVÁN , SZIRTES TAMÁS , ÜBERHARDT TAMÁS , RILL ATTILA , CSEHI ATTILA , HEGEDUS BÉLA 
Published: August 2010

Sodium‐liquid ammonia reduction has been used for over 50 years for removal of benzyl‐type protecting groups in peptide chemistry. Up until now a definitely blue end‐point has generally been accepted for detection of the completion of reaction. Systematic investigation with model compounds has revealed that this is not only unnecessary for the complete removal of the protecting groups but also that the application of sodium in excess results in many undesired transformations which can simply be suppressed or even eliminated by optimizing the sodium consumption.Cleavage of tert. ‐butyloxycarbonyl group and N‐Cα bond, reduction of carboxamide groups to carbinol derivatives, transpeptidation and formation of a hydantoin derivative have been observed in model experiments by using sodium in excess.
Preferred conformations of tert.‐butyloxycarbonyl‐L‐aminosuccinyl‐glycyl‐glycine methyl ester in the solid and solution state
Authors: CAPASSO S. , MATTIA C.A. , MAZZARELLA L. , ZAGARI A. 
Published: August 2010

Detailed conformational studies in the solid and solution state have been carried out on the blocked peptide tert.‐butyloxycarbonyl‐L‐aminosuccinyl‐glycyl‐glycine methyl ester, a model compound to study the conformational restrictions imposed by the presence of an aminosuccinyl residue in a polypeptide chain.The crystals belong to the monoclinic space group P21 with a = 5.022(1), b = 15.193(3), c = 11.173(2) Å, β = 95.09(1)± and V = 849.0(5) Å3. The structure was solved by direct methods and least‐squares refinement, which included the coordinates of hydrogen atoms, converged at R = 0.030 for 1648 *** reflections. Although in the solid state the molecule prefers an ***extended ***mation, the i.r. and 1H n.m.r. spectra in chloroform solution *** that a folded conformation of the type II′ β turn, also predicted by the potential energy calculations, is stable.
Synthesis of polypeptide models of collagen
Authors: GUANTIERI V. , TAMBURRO A.M. 
Published: August 2010

It is well known that the amino acid sequence of collagen contains a large number of tripeptide units such as Y‐X‐Gly, where Y and X can be any amino acid residue but most frequently are proline or hydroxyproline. Accordingly, several sequential polytripeptides, including repeating sequences of that type containing one or two imino acid residues, have been synthesized and studied in solution and/or in the solid state (1–14).In this paper we describe in detail the syntheses via active esters of four polytripeptides of the type poly(Pro‐X‐Gly) and poly(X‐Pro‐Gly), where X is isoleucine or norleucine. The general objective was to study the influence of hydrophobic residues on the stability of collagen three‐dimensional structure; in particular we were interested in the introduction of branching at Cβ in view of the recent calculations of Némethy & Scheraga (15). The Nle residue was introduced in order to obtain reference polymers without any branching in the side chain. By way of comparison, we have shown earlier that polymeric sequences where X is leucine (branching at the Cγ) possess collagen‐like structures in an appropriate milieu (10, 11). The results of both theoretical and experimental conformational studies on the polymers will be published in a forthcoming paper.Syntheses via p‐nitrophenyl esters are described for poly(Pro‐Ile‐Gly), poly(Ile‐Pro‐Gly), poly(Pro‐Nle‐Gly) and poly(Nle‐Pro‐Gly), four synthetic polytripeptide analogues of the non‐polar regions of collagens. The obtained polymers exhibit molecular weights in the range 5000–10000 as judged from viscosity measurements.
Syntheses, opioid binding affinities, and potencies of dynorphin A analogues substituted in positions 1, 6, 7, 8 and 10
Authors: KAWASAKI ANDREW M. , KNAPP RICHARD J. , WALTON AMANDA , WIRE WILLIAM S. , ZALEWSKA TERESA , YAMAMURA HENRY I. , PORRECA FRANK , BURKS THOMAS F. , HRUBY VICTOR J. 
Published: August 2010

Structural, stereochemical, stereoelectronic and conformational requirements for biological activity of dynorphin A1–11‐NH2analogues at opioid receptors were explored by substitution of Tyr1, Arg6, Arg7, Ile8and Pro10with other amino acid residues. Interestingly, substitution of Tyr1withNα‐Ac‐Tyrl, D‐Tyr1, Phe1orp‐BrPhe1led to analogues that were quite potent at κ opioid receptors, and additional substitution of Ile8with D‐Ala8and/or Pro10with D‐Pro10retained high potency in brain binding assay: [Nα‐Ac‐Tyr1]‐ (1), [D‐Tyr1]‐ (2) [Phe1]‐ (3), [Phe1. D‐Ala8]‐ (5), [p‐BrPhe1, D‐Alas]‐ (6), [Phe1, D‐Pro10]‐ (7) and [Phe1, D‐Ala8, D‐Pro10]‐Dyn A1–11‐NH2(8) had IC50(nM) binding affinities of 13.2, 18.6, 1.64, 1.26, 1.84, 2.44 and 1.62 nM, respectively. The D‐Phe1analogue 4, however, was only weakly active (610 nM). All of the analogues except 4 were modestly selective for κ vs. μ guinea pig brain opioid receptor (11‐ to 88–fold) and quite selective for κ vs. δ receptors (65–576). However, all of the analogues appeared to have very low or essentially no activity in the guinea pig ileum and mouse vas deference functional bioassays, and one analogue, 5, appeared to have weak antagonist activities. On the other hand, if constrained amino acids such as β‐methylphenylalanine or 1,2,3,4‐tetrahydroisoquinoline carboxylic acid, and hydroxyproline were placed in the 1 position, inactive analogues or analogues with greatly reduced potency and biological activity were obtained (compounds 12–14).It had previously been suggested that the Arg6and Arg7residues were critical for biological activity. However, when we replace either one of these residues, [Nle6]Dyn A1–11(9) and [Nle7]Dyn A1–11‐NH2(10) were both highly potent binders in κ receptor binding studies (IC50= 0.95 and 0.43 nM, respectively), and interestingly also were potent in μ and δ binding studies. Furthermore, both of the analogues were modestly potent in the GPI and MVD assays (94, 65 nM; 31, 81 nM, respectively). These results demonstrate that basic residues at positions 6 and 7 in dynorphin are not very important for binding to κ opioid receptors. Finally, many of the compounds reported here showed high selectivity for central vs. peripheral κ opioid receptors, with compound 4 being the most selective (63 000‐fold).
Relevance of sequence statistics for the properties of extremophilic proteins
Authors: BÖHM GERALD , JAENICKE RAINER 
Published: August 2010

The amino acid composition of proteins from mesophilic and extremophilic organisms is commonly assumed to reflect the mechanisms of molecular adaptation to extremes of physical conditions. In this context, halo‐philic behaviour has been attributed to significantly increased numbers of aspartic and glutamic acid residues. However, extending the analysis to a statistically relevant set of related proteins, dihydrofolate reductase from Halobacterium volcanii, as an example, shows that the increase in negative charge is found to be less significant than other exchanges of amino acids (e.g., Ala, Am, Arg, Lys, Phe, Ser). Thus, the high water binding capacity of negatively charged residues cannot be unambiguously correlated with the anomalous stability of halophilic proteins.A similar caveat holds for generalizations regarding the thermal stability of proteins. In this case, D‐glyceraldehyde‐3‐phosphate dehydrogenase from the hyperthermophilic bacterium Thermotoga maritima was compared with a number of mesophilic and moderately thermophilic homologs. Again, ‘traffic rules of stabilization’, in terms of amino acid changes in going from mesophilic to thermophilic proteins, cannot be given.
Modification of arginine residues in ovine prolactin by 1,2‐cyclohexanedione
Authors: CYMES GISELA D. , ATLASOVICH FABIÁN M. , CARIDAD JUAN J. , IGLESIAS M. MERCEDES , WOLFENSTEIN‐TODEL CARLOTA 
Published: August 2010

The reactivity of arginine residues in ovine prolactin was studied by reaction with 1,2‐cyclohexanedione. Kinetic analysis of the data showed a good fit with two simultaneous pseudo‐first‐order equations with apparent velocity constants of 0.28 and 1.2 × 10−2 min−1, corresponding to 1.8 ‘fast’ and 8.7 ‘slow’ residues, respectively. Modification led to a decrease in binding capacity to lactogenic rat liver receptors, and apparently the modification of the two ‘fast’ reacting arginine residues is responsible for the rapid loss of this capacity.The presence of a non‐reacting arginine has been described in human and bovine growth hormones, and it is located near the carboxy‐terminus. This lack of reactivity is probably due to the formation of a salt bridge, since the arginine residue becomes susceptible to modification once the peptide is separated from the rest of the molecule. This salt bridge is absent in ovine prolactin, since the homologous arginine residue is reactive with cyclohexanedione. This result suggests that there could be a difference between the three‐dimensional structure of ovine prolactin and of the growth hormones, at least near the carboxy‐terminal region of the molecule.
Different sequence environments of amino acid residues involved and not involved in long‐range interactions in proteins
Authors: TÜDÖS ÉVA , FISER ANDRÁS , SIMON ISTVAN 
Published: August 2010

No method has yet been available to decode information, hidden in the protein primary structure, on long‐range interactions of amino acids. Even a limited amount of information on long‐range interactions could help in conformational energy calculations of protein structures and could lead to a better understanding of how the primary structure of proteins determines their conformation.The sequence environments of amino‐acid residues were compared from the viewpoint of their participation in long‐range interactions. By using the simplest definition, residues were considered as partners in a long‐range interaction if they were at least 20 residues apart in the sequence and their Cα, distance was less than 7 Å.In spite of this rather crude definition, an analysis of 88 unrelated proteins has shown that the sequence environments (10 residues on each side) of those amino acids which are involved in long‐range interactions and of those which are not are significantly different according to the criteria of mathematical statistics. Moreover, in many cases the differences are so pronounced that the involvement of a given amino acid in long‐range interactions can be predicted from its sequence environment.