Investigations of cyanide as an infrared probe of hemeprotein ligand binding sites.
نویسندگان
چکیده
The measurement of infrared spectra for cyanide liganded to hemeproteins and hemins has been investigated. The hemeproteins included human methemoglobin A, lamprey methemoglobin, metchlorocruorin, horse metmyoglobin, and horseradish peroxidase. The hemins were dicyanide and monopyridine monocyanide species of deuteroporphyrin IX iron(III) and its 2,4-divinyl(proto) and 2,4-diacetyl derivatives. C-N stretch bands of low intensity detected near 2100 cm-1 exhibit changes in frequency, width, intensity, and isotope shift with changes in cyanide compound structure. Infrared band parameters are particularly sensitive to a change in oxidation state (Fe2+ versus Fe3+) and are affected to a lesser extent by changes in porphyrin ring substituent, ligand trans to the cyanide, and protein structure. Evidence of multiple conformers (i.e. multiple C-N stretch bands) was found for several hemeproteins. The cyanide infrared spectra provide direct evidence for cyanide binding as a metal cyanide (Fe--C identical to N) and against HCN being the ligand in nitrile-like bonding (Fe--N identical to C--H) in all the hemeprotein and hemin cyanides studied. With the reduced horseradish peroxidase cyanide, differences between infrared spectra for D2O and H2O solutions can result from hydrogen bonding between a protein amino acid residue and the distal atom of the cyanide (Fe--C identical to N...H+--R). The binding of cyanide to reduced iron (Fe2+) of a hemeprotein was only observed in the case of the reduced peroxidase. These findings demonstrate that cyanide infrared spectra can not only determine when cyanide is bound to a metalloprotein but can also provide information on how the cyanide is bonded to metal and on characteristics of the ligand binding site.
منابع مشابه
An Alkaline Phosphatase Lacking Wheat Germ Agglutinin Binding Sites Useful Enzyme for Lectin Assays with Comparable Activity to the Calf Enzyme
Despite the availability of various alkaline phosphatase (ALP) isoenzymes, the calf enzyme is being used in current enzyme assays as the detector enzyme. The glycosylation pattern of this enzyme makes it a suitable ligand for binding to wheat germ agglutinin lectin (WGA). As a result of this property, the enzyme can not be used as a conjugate with this lectin, and the calf enzyme conjugates can...
متن کاملAn infrared study of CO binding to heart cytochrome c oxidase and hemoglobin A. Implications re O2 reactions.
The CO stretch bands for CO liganded to hemoglobin A (1951 cm-l) and to fully reduced cytochrome c oxidase (1963.5 cm-‘) were used to determine the amount of CO bound, to follow the exchange of CO from the oxidase to Hb, and to probe the nature of the CO (and 0,) binding sites. A variety of oxidase preparations from bovine heart were explored; a convenient route to high purity oxidase at the co...
متن کاملAn Infrared Study of CO Binding to Heart Cytochrome c Oxidase and Hemoglobin A
The CO stretch bands for CO liganded to hemoglobin A (1951 cm-l) and to fully reduced cytochrome c oxidase (1963.5 cm-‘) were used to determine the amount of CO bound, to follow the exchange of CO from the oxidase to Hb, and to probe the nature of the CO (and 0,) binding sites. A variety of oxidase preparations from bovine heart were explored; a convenient route to high purity oxidase at the co...
متن کاملInteraction of Human Serum Albumin with Ethyl 2-[2-(dimethylamino)-4-(4-nitrophenyl)-1,3-thiazole-5-yl]-2-oxoacetate as a Synthesized Ligand
The interaction of human serum albumin with Ethyl 2-[2-(dimethylamino)-4-(4-nitrophenyl)- 1,3-thiazole-5-yl]-2-oxoacetate was investigated by using isothermal titration UV-visible spectrophotometry in tris-buffer, pH 7.4. According to these results, it was found that there are a set of 4 binding sites for this ligand on HSA with positive cooperativity in the binding process. This thiazole deriv...
متن کاملInfrared evidence of cyanide binding to iron and copper sites in bovine heart cytochrome c oxidase. Implications regarding oxygen reduction.
Cyanide binding to bovine heart cytochrome c oxidase at five redox levels has been investigated by use of infrared and visible-Soret spectra. A C-N stretch band permits identification of the metal ion to which the CN- is bound and the oxidation state of the metal. Non-intrinsic Cu, if present, is detected as a cyanide complex. Bands can be assigned to Cu+CN at 2093 cm-1, Cu2+CN at 2151 or 2165 ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of biological chemistry
دوره 260 6 شماره
صفحات -
تاریخ انتشار 1985