Abstract: An active protein can be easily, safely produced by a method comprising providing a first peptide fragment having a first amino acid sequence corresponding to part of an active protein and a second peptide fragment having a second amino acid sequence corresponding to the remaining part of the active protein, at least one of said first peptide fragment and said second peptide fragment being one which has been obtained by recombinant DNA technique or has been obtained by a method comprising producing a predetermined peptide fragment by recombinant DNA technique and deleting from or adding to said predetermined peptide fragment at its N-terminus at least one amino acid residue; and linking said first peptide fragment at its C-terminus to said second peptide fragment at its N-terminus.

Abstract: A novel physiologically active peptide represented by the following formula:BCysX.sub.1 CysX.sub.2 CysX.sub.3(wherein B stands for a hydrogen atom or a methionyl group, Cys a cysteine residue, X.sub.1 5 to 9 amino acid residues, X.sub.2 one amino acid residue, and X.sub.3 138 to 148 amino acid residues), which is excellent in physiological activities such as antiviral action, cell proliferation inhibitive action and NK (natural killer) cell activity enhancing action.

Abstract: AI-77 compounds, pharmaceutically acceptable salts thereof, and a process for the preparation thereof are described, said compounds having the formulae ##STR1## wherein: X is NR.sub.6 or O; Y is NHR.sub.5 or combine with Z to provide a link for bonding C and C; Z is H or combines with Y to provide a link for bonding C and C; R.sub.1, R.sub.3 and R.sub.5 are each H, R', --CH.sub.2 R, or --COR; R.sub.6 is H or R; R.sub.7 is H, R or CH.sub.2 R; R is a hydrocarbon group consisting of a saturated or unsaturated straight or branched aliphatic group of C.sub.1 to C.sub.17, an aromatic group of C.sub.6 to C.sub.10, a cage type group of C.sub.7 to C.sub.10, a monocyclic aliphatic group of C.sub.3 to C.sub.8, an aromatic-aliphatic group of C.sub.7 to C.sub.15, a heterocyclic hydrocarbon of C.sub.1 to C.sub.9, wherein the above hydrocarbons can be substituted with one or more groups selected from halogen, oxo, carboxyl, hydroxyl, a saturated or unsaturated straight or branched aliphatic group of C.sub.1 to C.sub.

Abstract: An 1,3,4-thiadiazole-5-thiol ester of the formula, ##STR1## wherein R is a hydrogen atom or a methyl group, a process for their preparation and a process for preparing a cephalosporin compound of the formula, ##STR2## wherein R is the same as defined above, using the above described 1,3,4-thiadiazole-5-thiol ester.

Abstract: An 1,3,4-thiadiazole-5-thiol ester of the formula, ##STR1## wherein R is a hydrogen atom or a methyl group, a process for their preparation and a process for preparing a cephalosporin compound of the formula, ##STR2## wherein R is the same as defined above, using the above described 1,3,4-thiadiazole-5-thiol ester.

Abstract: Novel 7.alpha.-methoxycephalosporin derivatives having a high antimicrobial activity. They are useful for the medical treatment of diseases infected by gram-positive bacteria and gram-negative bacteria. More particularly, they show an antimicrobial activity against bacteria such as Eschericha coli Proteus, Citrobacter and Enterobacter which bacteria have resistance to the conventionally employed cephalosporins, and they are effective for the medical treatment of diseases infected by these bacteria. Such 7.alpha.-methoxycephalosporin derivatives are prepared by a relatively simple method.

Abstract: Compounds represented by formula (I) ##STR1## wherein one of Z.sub.1 ', Z.sub.2 ', Z.sub.3 ' and Z.sub.4 ' represents R, another one of Z.sub.1 ', Z.sub.2 ', Z.sub.3 ' and Z.sub.4 ' represents Z, and the remaining two moieties of Z.sub.1 ', Z.sub.2 ', Z.sub.3 ' and Z.sub.4 ' represents a hydrogen atom and/or a protective group, one of R and Z represents A.sub.1 and the other represents A.sub.2, A.sub.1 being an acyl group having 14 to 22 carbon atoms which does not contain a carboxylic group and A.sub.2 being an acyl group having 2 to 14 carbon atoms and having one carboxyl group, X represents a hydrogen atom or a halogen atom (hereinafter referred to as Compound Ia); a 2,2'-anhydro product of Compound Ia wherein Z.sub.2 ' represents a hydrogen atom (hereinafter referred to as Compound Ib); an arabinosylation product of Compound Ia (hereinafter referred to as Compound Ic); a deamination product of Compound Ia (hereinafter referred to as Compound Id); a 2'-deoxy product of Compound Id wherein Z.sub.

Abstract: A compound represented by the formulae: ##STR1## wherein R.sub.1 and R.sub.2 are as defined hereinafter, useful as an anti-cancer or anti-tumor agent.

Abstract: A nucleotide derivative represented by the general formula: ##STR1## wherein R represents an acyl group having 14 - 22 carbon atoms and having an aliphatic acyl moiety; X represents a hydrogen atom, a halogen atom, an alkyl group having 1 - 4 carbon atoms, or a trifluoromethyl group; and at least one, but not all, of Y.sub.1, Y.sub.2, and Y.sub.3 represents a phosphate, a pyrophosphate, a triphosphate, or a salt thereof, the balance of Y.sub.1, Y.sub.2 and Y.sub.3 representing a hydroxyl group; or in case of ribosyl, Y.sub.1 and Y.sub.3, or Y.sub.2 and Y.sub.3 represent, at the same time, the aforesaid phosphate, pyrophosphate, triphosphate or salt thereof and the remaining group of Y.sub.1, Y.sub.2 or Y.sub.3 represents a hydroxyl group; or in case of arabinosyl, Y.sub.1 and Y.sub.2, or Y.sub.2 and Y.sub.3 represent, at the same time, the aforesaid phosphate, pyrophosphate, triphosphate or salt therof and the remaining group of Y.sub.1, Y.sub.2 or Y.sub.3 represents a hydroxyl group.

Abstract: N.sup.4 -Acyl-1-.beta.-D-arabinofuranosylcytosine-5'-esters represented by the formula ##STR1## wherein R.sup.1 represents an acyl group having 3 to 28 carbon atoms and R.sup.2 represents an XCH.sub.2, XCH.sub.2 CH.sub.2 or CH.sub.3 CHX group, wherein X represents a halogen atom, a (CH.sub.3).sub.2 N or (C.sub.2 H.sub.5).sub.2 N group.

Abstract: An N.sup.4 -acyl-1-.beta.-D-arabinofuranosylcytosine having the following formula ##SPC1##Wherein R is an aliphatic acyl group having 3 to 35 carbon atoms. The compounds of this invention are useful as a cancer chemotherapeutic agent for controlling tumors, e.g., in mice, an insecticide, and a fungicidal surface active agent.

Abstract: A novel physiologically active peptide represented by the following formula:BCysX.sub.1 CysX.sub.2 CysX.sub.3(wherein B stands for a hydrogen atom or a methionyl group, Cys a cysteine residue, X.sub.1 .[.5 to 9 amino acid residues.]. .Iadd.an isoleucylvalylleucylglycylserylleucylglycine residue, .Iaddend.X.sub.2 .[.one amino acid residue.]. .Iadd.a tyrosine residue.Iaddend., and X.sub.3 .[.138 to 148 amino acid residues.]. .Iadd.a specific sequence of 143 amino acid residues as defined herein.Iaddend.), which is excellent in physiological activities such as antiviral action, cell proliferation inhibitive action and NK (natural killer) cell activity enhancing action.Iadd., and a short sequence peptide represented by the above-mentioned X.sub.3 .Iaddend..