Spectra myoglobin

A sample of the protein, horse heart myoglobin, was dissolved in acidified aqueous acetonitrile (1% formic acid in HjO/CHjCN, 1 1 v/v) at a concentration of 20 pmol/1. This sample was injected into a flow of the same solvent passing at 5 pl/min into the electrospray source to give the mass spectrum of protonated molecular ions [M + nH] shown in (a). The measured ra/z values are given in the table (b), along with the number of protons (charges n) associated with each. The mean relative molecular mass (RMM) is 16,951,09 0.3 Da. Finally, the transformed spectrum, corresponding to the true relative molecular mass, is shown in (c) the observed value is close to that calculated (16,951.4), an error of only 0.002%. 

A typical electrospray spectrum of a high-molecular-weight material, i.e. that of horse heart myoglobin, is shown in Figure 4.11. Each of the ions observed arises from attachment of a different number of protons, and an equivalent number of charges, to the intact molecule. 

Figure 4.11 Electrospray spectrum of horse heart myoglobin.

Table 4.1 Molecular weight of horse heart myoglobin calculated from four adjacent pair of ions observed in its electrospray mass spectrum...

If we consider the electrospray spectrum of horse heart myoglobin shown pre-vionsly (see Figure 4.11), the information given in Table 4.1 may be obtained by application of the above equations. The precision and accuracy of these measurements are also shown in this table. 

Determine the charge state on the ion of m/z 1060.71 in the mass spectrum shown in Figure 4.11 by using the methodoiogy outlined above. From this, calculate the molecular weight of horse heart myoglobin. 

Sage et al. reported the complete vibrational spectrum of the iron site in deoxy-and CO-myoglobin [110]. The spectrum of photolyzed CO-myoglobin (frozen solution) resembles that of Mb. Because of high-resolution and reasonable statistics, they... 

The biochemical activity and accessibility of biomolecule-intercalated AMP clays to small molecules was retained in the hybrid nanocomposites. For example, the absorption spectrum of the intercalated Mb-AMP nanocomposite showed a characteristic soret band at 408 nm associated with the intact prosthetic heme group of the oxidised protein (Fe(III), met-myoglobin) (Figure 8.9). Treatment of Mb with sodium dithionite solution resulted in a red shift of the soret band from 408 to 427 nm, consistent with the formation of intercalated deoxy-Mb. Reversible binding of CO under argon to the deoxy-Mb-AMP lamellar nanocomposite was demonstrated by a shift in the soret band from 427 to 422 nm. Subsequent dissociation of CO from the heme centre due to competitive 02 binding shifted the soret band to 416nm on formation of intercalated oxy-Mb. 

Myoglobin can also bind CO, and sol-gel with entrapped myoglobin can be used as the sensor for CO by taking advantages of the changes in the absorption spectrum due to protein-CO interaction. 

Structure in solution Bombyx mori (Iizuka and Yang, 1966 Yao et al, 2004), MA, MI, FLAG, and CYL (Dicko et al., 2004b), Acinous and Pyriform (Fig. 8), Antheraea pemyi (Tsukada et al, 1994). The helix-like structure is loosely defined as a structure with a CD spectrum similar to myoglobin. /(-Spiral structure is defined as a super helical structure formed of straight sections and /(-turns. 

Fig. 11.21. Partial high-resolution ESI spectrum (R = 20,000) of a mixture of lysozyme and myoglobin. Reproduced from Ref. [103] by permission. John Wiley Sons, 1993.

Fig. 10.1 Effect of buffer composition on the ESI-FTICR-MS spectrum of myoglobin. The spectrum in (a) was acquired from a solution containing 2 pM myoglobin in 50% MeOH, 49% H2O, and 1% HOAc. Peaks corresponding to apomyoglobin and free heme dominate the spectrum. The spectrum in (b) was acquired from a solution...

Hb possesses both 4 and 5-coordinate forms as demonstrated by the Raman spectra (Figure 1) and the spj it Soret band of the absorption spectrum (9,36). In contrast, Mb shows only the red Soret component and the Raman lines characteristic of the 5-coordinate form. Thus, myoglobin s R-like structure favors the 5-coordinate form. The R/T difference in affinity for histidine might also be expected to reveal itself in the strength of the Ni-histidine bond. In native Fe hemoglobin, the Fe-histidine bond increases in strength upon conversion from the T to R structure (31,39). 

Figure 2. Raman spectra of Ni-reconstituted myoglobin and natural abundance Ni-reconstituted myoglobin and the difference spectrum. The Raman difference spectrum shows clearly the isotope shift in the 270-cm line to 260 cm and the larger (intensity-wise) shift in the Ni-histidine mode at 240 cm. ...

Selected entries from Methods in Enzymology [vol, page(s)] Application in fluorescence, 240, 734, 736, 757 convolution, 240, 490-491 in NMR [discrete transform, 239, 319-322 inverse transform, 239, 208, 259 multinuclear multidimensional NMR, 239, 71-73 shift theorem, 239, 210 time-domain shape functions, 239, 208-209] FT infrared spectroscopy [iron-coordinated CO, in difference spectrum of photolyzed carbonmonoxymyo-globin, 232, 186-187 for fatty acyl ester determination in small cell samples, 233, 311-313 myoglobin conformational substrates, 232, 186-187]. 

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