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Details for Patent: 5,814,297

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Title:	Technetium-99m labeled peptides for imaging having a single thiol containing moiety
Abstract:	The invention relates to radiolabeled imaging of a mammalian body. The invention in particular provides for reagents labeled with technetium-99m for such imaging. The invention provides peptides which bind Tc-99m and which can be targeted to specific sites within a mammalian body.
Inventor(s):	Dean; Richard T. (Bedford, NH), McBride; William (Manchester, NH), Buttram; Scott (Derry, NH)
Assignee:	Diatide, Inc. (Londonderry, NH)
Filing Date:	Jun 06, 1995
Application Number:	08/471,741
Claims:	1. A radioactively-labeled peptide for imaging a target site within a mammalian body, comprising: a) a specific binding peptide having between 4 and 100 amino acid residues that concentrates at said target site; b) a complexing group covalently linked to the specific binding peptide, said group comprising a single thiol moiety having a formula: wherein A is H or HOOC B is H, SH or NHR", where R" is H or lower alkyl; X is SH or NHR", where R" is H or lower alkyl; R and R' are independently H or lower alkyl; n is 0, 1,or 2; and where B is NHR", X is SH and n is 1 or 2; where X is NHR", B is SH and n is 1 or 2; where B is H, A is HOOC, X is SH and n is 0 or 1; said group further comprising a dipeptide covalently linked to A when A is COOH, or to B when B is NH.sub.2, or to X when X is NH.sub.2 ; and c) a radioactive isotope complexed to the complexing group. 2. The complex of claim 1, wherein the isotope is technetium-99m. 3. The complex of claim 2 formed by reacting technetium-99m and a reducing agent with a peptide comprising: a) a specific binding peptide having between 4 and 100 amino acid residues that concentrates at a target site within a mammalian body; and b) a complexing group covalently linked to the specific binding peptide, said group comprising a single thiol moiety having a formula: wherein A is H or HOOC B is H, SH or NHR", where R" is H or lower alkyl; X is SH or NHR", where R" is H or lower alkyl; R and R' are independently H or lower alkyl; n is 0, 1, or 2; and where B is NHR", X is SH and n is 1 or 2; where X is NHR", B is SH and n is 1 or 2; where B is H, A is HOOC, X is SH and n is 0 or 1; said group further comprising a dipeptide covalently linked to A when A is COOH, or to B when B is NH.sub.2, or to X when X is NH.sub.2. 4. The complex of claim 3, wherein the reducing agent is a dithionite ion, a stannous ion, or a solid-phase reducing agent. 5. The complex of claim 2 formed by ligand exchange of a prereduced technetium-99m complex with a peptide comprising a) a specific binding peptide having between 4 and 100 amino acid residues that concentrates at a target site within a mammalian body; and b) a complexing group covalently linked to the specific binding peptide, said group comprising a single thiol moiety having a formula: wherein A is H or HOOC B is H, SH or NHR", where R" is H or lower alkyl; X is SH or NHR", where R" is H or lower alkyl; R and R' are independently H or lower alkyl; n is 0, 1,or2; and where B is NHR", X is SH and n is 1 or 2; where X is NHR", B is SH and n is 1 or 2; where B is H, A is HOOC, X is SH and n is 0 or 1; said group further comprising a dipeptide covalently linked to A when A is COOH, or to B when B is NH.sub.2, or to X when X is NH.sub.2.