Resonance Raman spectra of octaethylporphyrinato‐Ni(II) and meso‐deuterated and 15N substituted derivatives. II. A normal coordinate analysis
15 Nov 1978-Journal of Chemical Physics (American Institute of Physics)-Vol. 69, Iss: 10, pp 4526-4534
TL;DR: In this article, normal coordinate calculations are carried out for all the inplane modes of octaethylporphyrinato-Ni (II) and its meso-deuterated and 15N substituted derivatives.
Abstract: Normal coordinate calculations are carried out for all the in‐plane modes of octaethylporphyrinato‐Ni (II) and its meso‐deuterated and 15N substituted derivatives. With 37 constants of a modified Urey–Bradley force field and a structural model with D4h symmetry, 59 resonance Raman lines (A1g+B1g +A2g+B2g) and 38 infrared bands (Eu) of these three molecules are assigned. The vibrational modes of the Raman active species are represented in terms of the Cartesian atomic displacement vectors. Based on the present results, some important resonance Raman lines of hemoproteins are interpreted. The so‐called ’’oxidation state maker’’ (Band IV) is due to an in‐phase breathing‐like mode of four pyrrole rings although being somewhat deformed by the large contribution of the Cα–N symmetric stretching term. The spin state sensitive Raman lines, namely, Band I and III, are associated mainly with methine bridge (Cα–Cm) stretching modes. Two prominent anomalously‐polarized Raman lines of hemoproteins around 1580 and 1300...
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TL;DR: New insights are provided into the vibrational dynamics, electronic structure and resonant enhancement of heme moieties within functional erythrocytes at near-IR excitation wavelengths and non-totally symmetric B1g modes in oxygenated cells.
Abstract: Resonance Raman spectra of oxygenated and deoxygenated functional erythrocytes recorded using 785 nm laser excitation are presented. The high-quality spectra show a mixture of enhanced A1g, A2g, B1g, B2g, Eu and vinyl modes. The high sensitivity of the Raman system enabled spectra from four oxygenation and deoxygenation cycles to be recorded with only 18 mW of power at the sample over a 60-minute period. This low power prevented photo-/thermal degradation and negated protein denaturation leading to heme aggregation. The large database consisting of 210 spectra from the four cycles was analyzed with principal components analysis (PCA). The PC1 loadings plot provided exquisite detail on bands associated with the oxygenated and deoxygenated states. The enhancement of a band at 567 cm−1, observed in the spectra of oxygenated cells and the corresponding PC1 loadings plot, was assigned to the Fe–O2 stretching mode, while a band appearing at 419 cm−1 was assigned to the Fe–O–O bending mode based on previous studies. For deoxygenated cells, the enhancement of B1g modes at 785 nm excitation is consistent with vibronic coupling between band III and the Soret transition. In the case of oxygenated cells, the enhancement of iron-axial out-of-plane modes and non-totally symmetric modes is consistent with enhancement into the y,z-polarized transition \({\text{a}}_{{{\text{iu}}}} {\left( {\text{ $ \pi $ }} \right)} \to {\text{d}}_{{{\text{xz}}}} + {\text{O}}_{{\text{2}}} {\left( {{\text{ $ \pi $ }}_{{\text{g}}} } \right)}\) centered at 785 nm. The enhancement of non-totally symmetric B1g modes in oxygenated cells suggests vibronic coupling between band IV and the Soret band. This study provides new insights into the vibrational dynamics, electronic structure and resonant enhancement of heme moieties within functional erythrocytes at near-IR excitation wavelengths.
257 citations
TL;DR: Direct monitoring of the cooling dynamics of the heme cofactor within the globin matrix allows the characterization of the vibrational energy flow through the protein moiety and to the water bath.
Abstract: The formation of vibrationally excited heme upon photodissociation of carbonmonoxy myoglobin and its subsequent vibrational energy relaxation was monitored by picosecond anti-Stokes resonance Raman spectroscopy. The anti-Stokes intensity of the nu4 band showed immediate generation of vibrationally excited hemes and biphasic decay of the excited populations. The best fit to double exponentials gave time constants of 1.9 +/- 0.6 and 16 +/- 9 picoseconds for vibrational population decay and 3.0 +/- 1.0 and 25 +/- 14 picoseconds for temperature relaxation of the photolyzed heme when a Boltzmann distribution was assumed. The decay of the nu4 anti-Stokes intensity was accompanied by narrowing and frequency upshift of the Stokes counterpart. This direct monitoring of the cooling dynamics of the heme cofactor within the globin matrix allows the characterization of the vibrational energy flow through the protein moiety and to the water bath.
253 citations
TL;DR: It seems rather likely that the proximal histidine is very strongly hydrogen-bonded at both sides of the transition but an appreciable strain is exerted to the Fe-N,(His) bond at the alkaline side presumably due to a conformation change of the polypeptide chain upon ionization of distal histidine.
207 citations
TL;DR: It is proposed that the 216 cm−1 line of deoxy Hb is associated primarily with the FeNe(HisF8) stretching mode and accordingly that the Fe £1,000,000 bond is stretched in the T state due to a strain exerted by globin.
198 citations
TL;DR: SERS spectra of whole human blood, blood plasma, and red blood cells on Au nanoparticle SiO(2) substrates excited at 785 nm have been observed and can have significant impact in the area of clinical diagnostics, blood supply management, and forensics.
Abstract: SERS spectra of whole human blood, blood plasma, and red blood cells on Au nanoparticle SiO(2) substrates excited at 785 nm have been observed. For the sample preparation procedure employed here, the SERS spectrum of whole blood arises from the blood plasma component only. This is in contrast to the normal Raman spectrum of whole blood excited at 785 nm and open to ambient air, which is exclusively due to the scattering of oxyhemoglobin. The SERS spectrum of whole blood shows a storage time dependence that is not evident in the non-SERS Raman spectrum of whole blood. Hypoxanthine, a product of purine degradation, dominates the SERS spectrum of blood after ~10-20 h of storage at 8 °C. The corresponding SERS spectrum of plasma isolated from the stored blood shows the same temporal release of hypoxanthine. Thus, blood cellular components (red blood cells, white blood cells, and/or platelets) are releasing hypoxanthine into the plasma over this time interval. The SERS spectrum of red blood cells (RBCs) excited at 785 nm is reported for the first time and exhibits well-known heme group marker bands as well as other bands that may be attributed to cell membrane components or protein denaturation contributions. SERS, as well as normal Raman spectra, of oxy- and met-RBCs are reported and compared. These SERS results can have significant impact in the area of clinical diagnostics, blood supply management, and forensics.
191 citations
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TL;DR: Metalloporphyrins, most notably the iron porphyrin, observe clearly defined, internally consistent, structural principles that promise to be fully applicable to the hemes in the several families of the hemoproteins.
Abstract: Metalloporphyrins, most notably the iron porphyrins, observe clearly defined, internally consistent, structural principles that promise to be fully applicable to the hemes in the several families of the hemoproteins.
271 citations
205 citations
TL;DR: In this paper, the infra-red spectra of Cu(acac)2, Pd, Pt, Mn, Cd, Cc, Cr, Co, Co(cac)3, Cr(cc)4, Rc, Rh(ccc)3 and Mn, cc)3 have been measured in the region from 4000 to 60 cm−1, and normal co-ordinate treatments have been made for the 1:2 and 1:3 complex.
196 citations
TL;DR: In this paper, high resolution resonance Raman spectra of octaethylporphyrinato-Ni(II) [Ni (OEP), its meso-deuterated and 15N substituted derivatives were measured.
Abstract: High resolution resonance Raman spectra of octaethylporphyrinato‐Ni(II) [Ni (OEP)], its meso‐deuterated and 15N substituted derivatives were measured. With excitation near the O–1 transition, about 90 nonfundamental modes and previously unrecognized fundamental modes were observed for each derivative. The analysis of the nonfundamental Raman lines allowed the determination of all the fundamental frequencies in the A1g, B1g, A2g, and B2g species of D4h symmetry. Experimental classification of depolarized Raman lines to the B1g and B2g species was worked out. Combinations of B1g and B2g modes give rise to anomalously‐polarized Raman lines while combinations of B1g modes and of B2g modes give rise to polarized lines. The Raman lines of the B1g species of Ni(OEP) with D4h symmetry are correlated with those in the Ag species of H2(OEP) with D2h symmetry while the B2g species of D4h is correlated with the B1g species of D2h. The experimental frequencies of fundamental modes thus determined satisfied the product...
150 citations