Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Site-specific presentation of oligosaccharides in the context of carrier proteins can influence markedly their recognition by carbohydrate-binding proteins. On RNaseB, the Man5-9 N-glycans at Asn-34 are bound by the serum lectin conglutinin when the glycoprotein is reduced and denatured, but there is no binding to the N-glycans on the native form of RNaseB. The RNaseB Man8, which is a glycoform preferentially bound by conglutinin, is the subject of the present study. The conformational behavior of the protein-linked oligosaccharide Man8 is investigated on the native and on the reduced and denatured RNaseB, using a combination of NMR and theoretical calculations. Quantitative data on the NOESY crosspeaks have been obtained, thereby allowing the comparison of mobilities of homologous linkages within the glycan chain. Oligosaccharide conformations compatible with the NMR data have been explored by molecular modeling of the free oligosaccharide, using two different force fields (AMBER and SYBYL). There are some differences between the results produced by the two force fields, the AMBER simulations providing a better agreement with the experimental data. The results indicate that both on the native and on the reduced heat-denatured glycoprotein, the RNase Man8 oligosaccharide exhibits a conformational behavior very similar to that of the free oligosaccharide. However, this conformational freedom of the N-glcyan does not amount to full availability for carbohydrate-recognition proteins and enzymes.
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PMID:Conformational studies of the Man8 oligosaccharide on native ribonuclease B and on the reduced and denatured protein. 1109 72

The English isolate of rat cytomegalovirus (RCMV) encodes a 20-kDa protein with a C-type lectin-like domain that is expressed in the delayed-early and late phases of the viral replication cycle. Genomic sequence analysis of the restriction fragment KpnR of RCMV revealed significant homology to several C-type lectin-containing molecules implicated in natural killer (NK) and T-cell interactions, as well as genes from four poxviruses and African swine fever virus. The gene is spliced into five exons and shows a splicing pattern with exon boundaries similar to those observed in the human differentiation antigen CD69. The cap site of the gene was mapped by RNase protection, 5' rapid amplification of cDNA ends, and primer extension experiments. This analysis demonstrated that the core promoter of the RCMV lectin-like gene contains a GATA rather than a TATA box. Splicing patterns were confirmed with isolates from an infected-cell cDNA library. A unique aspect of the protein is that its translation is not initiated by the canonical methionine but rather by alanine. To study its role in virus replication and pathogenesis, a recombinant virus was constructed in which the gene is interrupted. Replication in tissue culture was similar to that of wild-type virus.
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PMID:Identification and characterization of a spliced C-type lectin-like gene encoded by rat cytomegalovirus. 1113 73

Conglutinin is a serum lectin of the innate immune system, which binds high mannose N-glycans when these are appropriately presented on proteins. Here we use the conglutinin-ribonuclease B (RNaseB)-recognition system as a model to investigate the structural basis of selective recognition of protein-bound oligosaccharides by this carbohydrate-binding receptor. Conglutinin shows little binding to the isolated RNaseB-Man(8 )glycoform, and no binding to Man(5-6) glycoforms. In contrast, when the protein moiety is reduced and denatured we observe that conglutinin binds strongly to the isolated RNaseB-Man(8) glycoform and weakly to the Man(5-6) glycoforms. These results are in accord with observations on the binding to the N-glycans in the absence of carrier protein. NMR analyses of native RNaseB-Man(8) and -Man(5-6) glycoforms reveal that the three-dimensional structure of the protein moiety is essentially identical to that of non-glycosylated RNase (RNaseA). Thus there are no perceptible differences between the RNase protein forms that could account for differential availability of the N-glycan for conglutinin-binding. After reduction and denaturation, the NMR spectrum became typical of a non-structured polypeptide, although the conformational preferences of the N-glycosidic linkage were unchanged, and most importantly, the Man(8 )oligosaccharide retained the average conformational behavior of the free oligosaccharide irrespective of the carrier protein fold. This conformational freedom is clearly not translated into full availability of the oligosaccharide for the carbohydrate-recognition protein. We propose, therefore, that the differing bioactivity of the N-glycan is a reflection of the existence of different geometries of presentation of the carbohydrate determinant in relation to the protein surface within the glycan:carrier protein ensemble.
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PMID:Carrier protein-modulated presentation and recognition of an N-glycan: observations on the interactions of Man(8) glycoform of ribonuclease B with conglutinin. 1118 59

The sialic acid binding lectin from bullfrog Rana catesbeiana oocyte (cSBL) is known to have anti-tumor activity. In order to investigate the relationship between the net charge of cSBL and its anti-tumor effect, cSBL was modified with a water-soluble carbodiimide (EDC) in the presence of three kinds of nucleophiles, taurine, glycine methylester and ethylenediamine. cSBL having four carboxyl groups was partially modified (ca. 2 residues). The anti-tumor activity of modified cSBLs was in the order of ethylenediamine-modified cSBL > glycine methylester-modified cSBL > taurine modified cSBL > or = native cSBL. The results suggested that anti-tumor activity seems to increase with the increase in positive net charge, possibly enhancing the interaction of cSBL with sialoglycoprotein on the surface of tumor cells. The ribonuclease activity of ethylenediamine-modified cSBL decreased with the progress of the reaction, but the number of internalized molecules in the tumor cell increased. Thus, for antitumor activity, a higher incorporation of cSBL with reasonable RNase activity seems to be more important than total RNase activity.
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PMID:Effect of modification of the carboxyl groups of the sialic acid binding lectin from bullfrog (Rana catesbeiana) oocyte on anti-tumor activity. 1155 80

RC-RNases are ribonucleases from Rana catesbeiana oocytes with pyrimidine-guanine sequence specificity. They also possess cell cytotoxicity and lectin activity. Protein crystals of three RC-RNase isozymes, RC-RNase 3, RC-RNase 4 and RC-RNase 6, were grown in various crystal systems under different conditions. Crystals of RC-RNase3 belong to the orthorhombic C222(1) space group, with unit-cell parameters a = 66.66, b = 97.38, c = 85.74 A. Crystals of RC-RNase 4 belong to the trigonal space group P3(1) or P3(2), with unit-cell parameters a = b = 32.22, c = 92.12 A. Crystals of RC-RNase 6 complexed with cytidylyl 2'-5' guanosine belong to the tetragonal space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = b = 61.80, c = 65.96 A.
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PMID:Crystallization and preliminary X-ray diffraction analysis of cytotoxic ribonucleases from bullfrog Rana catesbeiana. 1167 49

A protein designated unguilin was isolated from seeds of the black-eyed pea (Vigna unguiculata). It possesses a molecular weight of 18 kDa and an N-terminal sequence resembling that of cyclophilins and the cyclophilin-like antifungal protein from mung beans, and was adsorbed on Affi-gel blue gel and CM-Sepharose. Unguilin exerted an antifungal effect toward fungi including Coprinus comatus, Mycosphaerella arachidicola, and Botrytis cinerea. In addition, unguilin was capable of inhibiting human immunodeficiency virus-1 reverse transcriptase and the glycohydrolases a- and beta-glucosidases which are involved in HIV infection. Unguilin was devoid of lectin and ribonuclease activities. It inhibited methyl-3H-thymidine uptake by mouse splenocytes and it weakly inhibited translation in a rabbit reticulocyte lysate system. Unguilin resembles mungin in some aspects, but differs from it in others.
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PMID:Isolation of unguilin, a cyclophilin-like protein with anti-mitogenic, antiviral, and antifungal activities, from black-eyed pea. 1173 86

A homodimeric lectin adsorbed on Affi-gel blue gel and CM-Sepharose and possessing a molecular weight of 67 kDa was isolated from red kidney beans. The hemagglutinating activity of this lectin was inhibited by glycoproteins but not by simple sugars. The lectin manifested inhibitory activity on human immunodeficiency virus-1 reverse transcriptase and alpha-glucosidase. The N-terminal sequence of the lectin exhibited some differences from previously reported lectins from Phaseolus vulgaris but showed some similarity to chitinases. It exerted a suppressive effect on growth of the fungal species Fusarium oxysporum, Coprinus comatus, and Rhizoctonia solani. The lectin had low ribonuclease and negligible translation-inhibitory activities.
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PMID:Isolation of a homodimeric lectin with antifungal and antiviral activities from red kidney bean (Phaseolus vulgaris) seeds. 1173 88

The anti-tumor activity of sialic acid binding lectin from Rana catesbeiana (cSBL) was increased by chemical modification with a water-soluble carbodiimide (EDC) in the presence of nucleophiles such as ethylenediamine and glycine methylester. Investigations on ribonuclease (RNase) activities of the modified cSBLs were conducted to elucidate the fundamental mechanisms underlying enhancement of the anti-tumor activity conferred by these modifications. The following three characteristics were observed with modification. (i) RNase activity of the modified cSBL was enhanced towards double stranded RNA and RNA-oligo dA hybrids. The activity increase was observed even under physiologic ionic strength conditions; (ii) RNase activity of the modified cSBL towards single stranded RNA and poly U decreased, while the activity towards poly C was unaffected; (iii) the base preference of the B2 base recognition site of modified cSBL decreased for guanine. On the contrary, the preference for cytosine and adenine increased. This result may explain why the RNase activity towards poly C was not affected by EDC-modification as mentioned above.
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PMID:Enzymatic properties of sialic acid binding lectin from Rana catesbeiana modified with a water-soluble carbodiimide in the presence of various nucleophiles. 1176 3

A protein designated chickpea cyclophilin-like antifungal protein (CLAP) was isolated from seeds of the chickpea (Cicer arietinum). Chickpea CLAP was characterized by a molecular weight of 18 kDa and an N-terminal sequence homologous to cyclophilins. The protein was isolated with a procedure involving affinity chromatography on Affi-gel blue gel and ion exchange chromatography on CM-Sepharose. In addition to an inhibitory effect on the growth of fungi including Rhizoctonia solani, Mycosphaerella arachidicola and Botrytis cinerea, the protein was capable of inhibiting human immunodeficiency virus-1 reverse transcriptase. Chickpea CLAP did not possess lectin and ribonuclease activities but it weakly inhibited translation in a rabbit reticulocyte lysate system. The protein stimulated 3H-thymidine incorporation by mouse splenocytes.
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PMID:Isolation of a new cyclophilin-like protein from chickpeas with mitogenic, antifungal and anti-HIV-1 reverse transcriptase activities. 1184 97

A single-chained protein designated solenin was isolated from Solenognathus hardwickii, a fish used as traditional Chinese medicinal material. Solenin was capable of inhibiting translation in a cell-free rabbit reticulocyte lysate system with an IC(50) of 2 microM and expressing a ribonuclease activity of 0.8U/mg toward yeast transfer RNA, but it lacked N-glycosidase activity characteristic of ribosome inactivating proteins Solenin exhibited a molecular weight of 18kDa and possessed an N-terminal sequence AHDAEVNEVKAQVAA. The protein was adsorbed on three types of chromatographic media: Affi-gel blue gel, CM-Sepharose and Mono S. It was devoid of antifungal and lectin activities.
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PMID:Solenin, a novel protein with translation-inhibiting activity from the traditional Chinese medicinal fish, the sea dragon Solenognathus hardwickii. 1194 93


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