sup 195 Pt NMR spectroscopy of ( sup 15 N) peptide complexes

Journal Article · Wed Sep 05 04:00:00 EDT 1990 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00343a053· OSTI ID:6113297

Schwederski, B E; Lee, H D; Margerum, D W ^[1]

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1. Purdue Univ., West Lafayette, IN (USA)

The reactions of PtCl{sub 4}{sup 2{minus}} with oligoglycyl peptides in aqueous solution proceed by amine coordination followed by sequential deprotonation and coordination of available peptide nitrogens. Complexes of PtLCl{sub 3}{sup 2{minus}}, Pt(H{sub {minus}1}L)X{sub 2}{sup 2{minus}}, Pt(H{sub {minus}2}L)X{sup {minus}}, and Pt(H{sub {minus}3}G{sub 4}){sup 2{minus}} (where L = triglycine (G{sub 3}), triglycinamide (G{sub 3}a), or tetraglycine (G{sub 4}), X = Cl{sup {minus}} or OH{sup {minus}}, and H{sub {minus}n} designates the number of deprotonated-N(peptide) bonds) are characterized by use of {sup 195}Pt NMR spectroscopy. Several bis(peptide) complexes also are identified. Structural assignments are made on the basis of coupling constants with ({sup 15}N)peptides. The magnitude of the J{sub Pt-N} coupling constants are Pt-N{sup {minus}}(peptide) > Pt-N(amine) {approx} Pt-NH{sub 3} (N{sup {minus}} denotes the deprotonated peptide nitrogen); the trans influence on Pt-N(amine) or Pt-N{sup {minus}}(peptide) is N{sup {minus}}(peptide) >> OH{sup {minus}}, RNH{sub 2}, NH{sub 3} > Cl{sup {minus}}. The chemical shifts for {sup 195}Pt are determined primarily by the elements coordinated to platinum(II) and secondarily by their chemical form. Monodentate amine coordination by the oligopeptide or the formation of the first chelate ring with amine and N{sup {minus}}(peptide) coordination gives an upfield shift of 110 ppm relative to the signal fore the corresponding Pt(NH{sub 3})X{sub 3}{sup {minus}} or cis-Pt(NH{sub 3}){sub 2}X{sub 2} complex. Two linked consecutive five-membered rings from peptide chelation cause an offsetting downfield shift of 120 ppm, and three linked consecutive five-membered chelates introduce an additional downfield shift of 250 ppm (relative to the coordination of one or two more NH{sub 3} molecules). 38 refs., 10 figs., 5 tabs.

• OSTI ID: 6113297
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 29:18; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
CHEMICAL PREPARATION
COMPLEXES
DATA
DAYS LIVING RADIOISOTOPES
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HEAVY NUCLEI
INFORMATION
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
NMR SPECTRA
NUCLEI
NUMERICAL DATA
ORGANIC COMPOUNDS
PEPTIDES
PLATINUM 195
PLATINUM COMPLEXES
PLATINUM ISOTOPES
PROTEINS
RADIOISOTOPES
SPECTRA
STABLE ISOTOPES
SYNTHESIS
TRANSITION ELEMENT COMPLEXES