Abstract: Provided is a stable isotope-labeled aliphatic amino acid enabling the assignment of the signal of an amino acid residue side chain by increasing to the maximum the observation sensitivity to an NMR signal of the same amino acid residue side chain, and allowing NOE (nuclear Overhauser effect) between protons in the amino acid residue to be observed. The stable isotope-labeled aliphatic amino acid is for constituting a protein and satisfies all of the following conditions (1) to (3): (1) two or more carbon atoms are labeled with 13C; (2) of two or more carbon atoms labeled with 13C, a carbon atom other than a carbon atom of a methyl group, which is capable of bonding to a hydrogen atom, has one 1H directly bonded thereto, while the carbon atom of the methyl group has at least one 1H directly bonded thereto; and (3) other carbon atoms adjacent to all the 13C are all 12C.

Abstract: Provided is a stable isotope-labeled aliphatic amino acid enabling the assignment of the signal of an amino acid residue side chain by increasing to the maximum the observation sensitivity to an NMR signal of the same amino acid residue side chain, and allowing NOE (nuclear Overhauser effect) between protons in the amino acid residue to be observed. The stable isotope-labeled aliphatic amino acid is for constituting a protein and satisfies all of the following conditions (1) to (3): (1) two or more carbon atoms are labeled with 13C; (2) of two or more carbon atoms labeled with 13C, a carbon atom other than a carbon atom of a methyl group, which is capable of bonding to a hydrogen atom, has one 1H directly bonded thereto, while the carbon atom of the methyl group has at least one 1H directly bonded thereto; and (3) other carbon atoms adjacent to all the 13C are all 12C.

Abstract: The present invention herein provides, for instance, a stable isotope-labeled phenylalanine wherein a carbon atom of the phenyl group linked to an amino acid residue is 13C, 2 to 4 carbon atoms of the remaining 5 carbon atoms constituting the phenyl group are 12C atoms to which deuterium atoms are bonded, and the remaining carbon atoms are 13C atoms to which hydrogen atoms are linked, and a stable isotope-labeled tyrosine wherein a carbon atom of the phenyl group linked to an amino acid residue is 13C, the carbon atom bonded to the hydroxyl group (OH group) of the phenyl group is 12C or 13C, 2 to 4 carbon atoms of the remaining 4 carbon atoms constituting the phenyl group are 12C atoms to which deuterium atoms are bonded, and the remaining carbon atoms are 13C atoms to which hydrogen atoms are linked.

Abstract: The present invention herein provides a combination of stable isotope-labeled aliphatic amino acids, which permits the structural analysis of a high molecular weight protein, in particular, a high molecular weight protein whose molecular weight exceeds 60 kDa. This is a combination of stable isotope-labeled amino acids which is characterized in that arginine (Arg), glutamine (Gln), glutamic acid (Glu), lysine (Lys), methionine (Met) and proline (Pro) satisfy the following requirements concerning the labelling pattern: (b) one of the methylene hydrogen atoms of at least one of the methylene groups is deuterated and the both of the two methylene hydrogen atoms of at least one of the methylene groups are likewise deuterated; and (d) when they each have a methyl group, the hydrogen atoms of the methyl group except for one of the same are deuterated, or the methyl group is completely deuterated.

Abstract: The present invention herein provides, for instance, a stable isotope-labeled phenylalanine wherein a carbon atom of the phenyl group linked to an amino acid residue is 13C, 2 to 4 carbon atoms of the remaining 5 carbon atoms constituting the phenyl group are 12C atoms to which deuterium atoms are bonded, and the remaining carbon atoms are 13C atoms to which hydrogen atoms are linked, and a stable isotope-labeled tyrosine wherein a carbon atom of the phenyl group linked to an amino acid residue is 13C, the carbon atom bonded to the hydroxyl group (OH group) of the phenyl group is 12C or 13C, 2 to 4 carbon atoms of the remaining 4 carbon atoms constituting the phenyl group are 12C atoms to which deuterium atoms are bonded, and the remaining carbon atoms are 13C atoms to which hydrogen atoms are linked.

Abstract: The present invention herein provides, for instance, a stable isotope-labeled phenylalanine wherein a carbon atom of the phenyl group linked to an amino acid residue is 13C, 2 to 4 carbon atoms of the remaining 5 carbon atoms constituting the phenyl group are 12C atoms to which deuterium atoms are bonded, and the remaining carbon atoms are 13C atoms to which hydrogen atoms are linked, and a stable isotope-labeled tyrosine wherein a carbon atom of the phenyl group linked to an amino acid residue is 13C, the carbon atom bonded to the hydroxyl group (OH group) of the phenyl group is 12C or 13C, 2 to 4 carbon atoms of the remaining 4 carbon atoms constituting the phenyl group are 12C atoms to which deuterium atoms are bonded, and the remaining carbon atoms are 13C atoms to which hydrogen atoms are linked.

Abstract: The present invention herein provides a combination of stable isotope-labeled aliphatic amino acids, which permits the structural analysis of a high molecular weight protein, in particular, a high molecular weight protein whose molecular weight exceeds 60 kDa. This is a combination of stable isotope-labeled amino acids which is characterized in that arginine (Arg), glutamine (Gln), glutamic acid (Glu), lysine (Lys), methionine (Met) and proline (Pro) satisfy the following requirements concerning the labelling pattern: (b) one of the methylene hydrogen atoms of at least one of the methylene groups is deuterated and the both of the two methylene hydrogen atoms of at least one of the methylene groups are likewise deuterated; and (d) when they each have a methyl group, the hydrogen atoms of the methyl group except for one of the same are deuterated, or the methyl group is completely deuterated.

Abstract: The present invention herein provides, for instance, a stable isotope-labeled phenylalanine wherein a carbon atom of the phenyl group linked to an amino acid residue is 13C, 2 to 4 carbon atoms of the remaining 5 carbon atoms constituting the phenyl group are 12C atoms to which deuterium atoms are bonded, and the remaining carbon atoms are 13C atoms to which hydrogen atoms are linked, and a stable isotope-labeled tyrosine wherein a carbon atom of the phenyl group linked to an amino acid residue is 13C, the carbon atom bonded to the hydroxyl group (OH group) of the phenyl group is 12C or 13C, 2 to 4 carbon atoms of the remaining 4 carbon atoms constituting the phenyl group are 12C atoms to which deuterium atoms are bonded, and the remaining carbon atoms are 13C atoms to which hydrogen atoms are linked.

Abstract: The present invention provides a stable isotope-labeled amino acid which is at least one of amino acids constituting a protein and which has at least one of the following labeling patterns: (a) hydrogen atoms except at least one hydrogen atom in one or more methylene groups are deuterated, (b) hydrogen atoms in one of prochiral gem-methyl groups are completely deuterated, (c) hydrogen atoms in prochiral methyl groups are partially deuterated, and (d) all hydrogen atoms except one of them in methyl group are deuterated and hydrogen atoms in the aromatic ring are partially deuterated. With the stable isotope-labeled amino acid, the deuteration of protein can be attained without damaging the NMR sensitivity of remaining hydrogen nucleus and, in addition, the rapid, accurate analysis of NMR spectrum of a high-molecular protein which is beyond the limitation in the prior art and the determination of the stereo-structure can be performed at the same time.

Abstract: The present invention provides a stable isotope-labeled amino acid which is at least one of amino acids constituting a protein and which has at least one of the following labeling patterns: (a) hydrogen atoms except at least one hydrogen atom in one or more methylene groups are deuterated, (b) hydrogen atoms in one of prochiral gem-methyl groups are completely deuterated, (c) hydrogen atoms in prochiral methyl groups are partially deuterated, and (d) all hydrogen atoms except one of them in methyl group are deuterated and hydrogen atoms in the aromatic ring are partially deuterated. With the stable isotope-labeled amino acid, the deuteration of protein can be attained without damaging the NMR sensitivity of remaining hydrogen nucleus and, in addition, the rapid, accurate analysis of NMR spectrum of a high-molecular protein which is beyond the limitation in the prior art and the determination of the stereo-structure can be performed at the same time.

Abstract: A purified ring peptide antibiotic of the following empirical formula:N.alpha.-(3-hydroxy-4-methyl-1-oxohexyl)-L-.alpha.,.gamma.-diaminobutyryl-L -isoleucyl-L-.alpha.,.gamma.-diaminobutyryl-D-phenylalanyl-L-leucyl-L-.alph a.,.gamma.-diaminobutyryl-D-valyl-L-leucyl-L-serine (9-1)-lactoneand which has the following structural formula: ##STR1## and wherein Dab represents 2,4-diamino butyric acid.