Raman studies of the helix‐to‐coil transition in poly‐<scp>L</scp>‐glutamic acid and poly‐<scp>L</scp>‐ornithine

Koenig, Jack L.; Frushour, Bruce G.

doi:10.1002/bip.1972.360110908

Cited by 78 publications

(51 citation statements)

References 16 publications

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“…This mode is shifted to 1001 cm -l on Ndeuteration and can be identified with the 1006 cm -l band in the Raman spectra. 6 The mode calculated at 554 cm -1 at {) = 0 goes to 59 I cm -1 at{)= 5n/9. The former is observed at 562 cm -l in Raman, 567cm-1 in IR and 552cm-1 in INS.…”

Section: Back Bone Modesmentioning

confidence: 91%

“…The other mode calculated 1426 cm -1 is a mixture of (CJ-OJ 2 -HJ) bending, CrH 2 scissor and side chain stretches. There is no corresponding observed (5) qi(Co---Cy-Hy0() (6) v(N---Cll( )( 4 7 </>(Cy-Ct5=0t51)(39) + w(Ct5=0t51)(16) + </>(Cy-Ct5-Ot52)(7) + </>(Ot52-Ct5=0t51)(6) + ,p(CfJ-Cy-Ct5) (5) </>(C1X-C=0)(21) + </>(C1X-C=N)(9) + v(C1X-C)(7) + </>(C-C1X-C/J)(6) + </>(N-C1X-C/J) (6) 409 ,p(C1X-C{J-Cy)(24) + </>(Cy-Ct5=0t5 1)(7) + </>(C-C1X-C/J)(7) + </>(N-C1X-C)(7) + </>(O=C=N)(5) 280 </>(N-C1X-C/J)(l8) + </>(C=N-C1X)(l4) + ,p(O=C=N)(l 1) + ,p(CfJ-Cy-Ct5)(9) + </>(CIX-C---0)(9) + </>(N-C1X-C) (7) ::i:::…”

Section: Side Chain Modesmentioning

confidence: 97%

“…It corresponds to the observed peak at 1419 cm -1 in Raman spectra. 6 The amide III mode which is mainly a combination of the (C!..!.. !N) stretch and N-H in-plane-bendings is calculated at 1274 cm -l and observed at 1283 cm -l and 1296 cm -l in IR and Raman spectra, 11 respectively.…”

Section: Back Bone Modesmentioning

confidence: 99%

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Heat Capacity and Vibrational Dynamics of Poly(L-glutamic acid) (α Helix)

Srivastava

Tandon

Gupta

et al. 1997

Polym J

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ABSTRACT:Poly(L-glutamic acid) is one of the polyamino acids containing a bulky side chain. At the room temperature and at pH < 5 it exists in ex helical conformation but at pH > 7 the ex helix is reduced to the random coil state. Normal mode analysis of poly(L-glutamic acid) has been reported by Sengupta and Krimm but no phonon dispersions have been reported so far. As a consequence both the thermodynamical studies and fuller interpretation of spectra remain incomplete. In the present communication we report complete normal mode analysis and full dispersion curves for poly(L-glutamic acid). A comparative study of ex and /32 forms of poly(L-glutamic acid) has been carried out in order to identify and to understand the spectral features due to two different conformations. Heat capacity has also been calculated by using density-of-states (g(v)). For the calculation of normal modes the Urey Bradley force field has been used. The normal modes for N-deuterated systems have also been studied to check the validity of the assignments and force field. Our results are in good agreement with the observed experimental data.

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Section: Back Bone Modesmentioning

confidence: 91%

Section: Side Chain Modesmentioning

confidence: 97%

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Heat Capacity and Vibrational Dynamics of Poly(L-glutamic acid) (α Helix)

Srivastava

Tandon

Gupta

et al. 1997

Polym J

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“…Although an irregular peptide chain also gives a C-C stretching band, the frequency of this band is generally higher than that of the cthelical C-C stretching. For example, the C-C stretching band of poly(L-glutamic acid) exhibits a frequency shift from 926 to 938 cm -1 upon helix-to-coil transition [24]. In the absence of Cu(II), PrP(84-103) gives two Raman bands in the frequency region; a 936 cm 1 band and a very weak band near 920 cm -1 (Fig.…”

Section: 'Oo Lz~oo 12oomentioning

confidence: 99%

Metal‐dependent α‐helix formation promoted by the glycine‐rich octapeptide region of prion protein

1996

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Prion diseases share a common feature in that the normal cellular prion .protein (PrP c) converts to a proteaseresistant isoform PrP ~c. The c¢-helix-rich C-terminal half of PrP c is partly converted into []-sheet in PrP so. We have examined by Raman spectroscopy the structure of an octapeptide PHGGGWGQ that appears in the N-terminal region of PrP c and a longer peptide containing the octapeptide region. The peptides do not assume any regular structure without divalent metal ions, whereas Cu(II) binding to the HGGG segment induces formation of co-helical structure on the C-terminal side of the peptide chain. The N-terminal octapeptide of prion protein may be a novel structural motif that acts as a promoter of c~-helix formation.

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“…744-747, pp. 169-177. early 1970s [12], [13], [14] and [15] broadened and intensified and presently encompasses even very specialized topics such as artificial lenses [16] or organ cultured cornea [17].…”

Section: Introductionmentioning

confidence: 99%

Development of cataract caused by diabetes mellitus: Raman study

Furić

Mohaček-Grošev

Hadžija

2005

Journal of Molecular Structure

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Diabetes mellitus succeeded by diabetic cataract was induced to experimental animals (Wistar rats) by applying an Alloxan injection. Eye properties deterioration were monitored from clinical standpoint and using Raman and infrared spectroscopies. All cases of developed cataract were followed by important changes in vibrational spectra, but Raman spectroscopy proved to be more useful because of larger number of resolved bands. Each kth Raman spectrum of diseased lens (in our notation k denotes disease age and cataract degree as described in chapter Alloxan diabetes) can be expressed as a sum of the Raman spectrum of healthy lens, I R , multiplied by a suitable constant c k , and the fluorescent background spectrum, I FB . We introduce the ratio of integrated intensities I FB and c k *I R as a physical parameter called fluorescent background index F FB . It turns out that F FB grows as cataract progresses and has its maximum at approx. 4, whence it decreases. F FB values are larger for 200-1800 cm −1 spectral interval than for 2500-4000 cminterval.In the same manner another quantity called water band index F W is defined for each Raman spectrum of diseased lens in the 2800-3730 cm −1 interval. It is the ratio of the integrated intensity from 3100 to 3730 cm −1 (water band interval) divided by the integrated intensity of the 2800-3100 cm −1 interval (C-H stretching region). F W increases monotonously with cataract progression with maximum at the end of monitored period (5 months).These two indices helped us to formulate a model describing disease development from the earliest molecular changes to its macroscopic manifestation. As glucose and other small saccharide molecules enter the lens tissue, they bind to crystallin and other proteins via O -and Sglycosidic linkages which occur probably at tyrosine and cystein sites. In Raman spectrum this corresponds to broad bands at 540 and 1100 cm −1 which grow together with the fluorescent background, because both contributions originate in nonenzimatically glycated proteins. The maximum of possible binding ends after approximately 4 months (cataract degree 4), but the water continues to enter the tissue and resides in water agglomerates.The lens impairing caused by fluorescent light scattering on aberrant glycoproteins and other fluorescent centers appears first and is usually associated with the ageing cataract, while deterioration of lens properties caused by increased binding of water steadily rises with glucose Furić, K., Mohaček-Grošev, V., Hadžija, M. (2005), ''Development of cataract caused by diabetes mellitus: Raman study '' Journal of Molecular Structure, and is characteristic of diabetic cataract. This interpretation is in agreement with electron microscopy results of other groups and with our preliminary findings obtained with light microscopy.

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Raman studies of the helix‐to‐coil transition in poly‐L‐glutamic acid and poly‐L‐ornithine

Cited by 78 publications

References 16 publications

Heat Capacity and Vibrational Dynamics of Poly(L-glutamic acid) (α Helix)

Heat Capacity and Vibrational Dynamics of Poly(L-glutamic acid) (α Helix)

Metal‐dependent α‐helix formation promoted by the glycine‐rich octapeptide region of prion protein

Development of cataract caused by diabetes mellitus: Raman study

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