Raman spectroscopic study of age-related structural changes in the lens proteins of an intact mouse lens

Abstract

Age-related structural changes in the lens proteins of a normal mouse lens have been monitored in situ by laser Raman spectroscopy. The Raman spectrum of an ICR-strain mouse lens nucleus showed virtually no change in the 550-850- and 900-1800-cm-1 regions as the mouse aged. Lens aging, however, did cause a significant intensity decrease of the Raman band at 880 cm-1 due to tryptophan residues, and the intensity decrease seems to be stepwise. This observation implies that a microenvironmental change of tryptophan residues takes place twice at different places of the lens proteins during normal aging. Particularly striking is that the intensity decrease of the band at 880 cm-1 proceeds in parallel with that of the Raman band at 2579 cm-1 due to a SH stretching mode for the first 4 months. Thus, the first microenvironmental change of tryptophan residues seems to be correlated with the formation of S-S bonds. In contrast to tryptophan residues, no evidence was observed of a microenvironmental change in tyrosine residues. In this respect, the structural changes of lens proteins in aging are sharply distinct from those in lens opacification, in which tyrosine as well as tryptophan residues undergo microenvironmental changes [Itoh, K., Ozaki, Y., Mizuno, A., & Iriyama, K. (1983) Biochemistry 22, 1773-1778]. The relative intensity of the band at 3390 cm-1 due to an OH stretching mode of lens water fell rapidly for the first 4 months and then decreased very gradually. The observation clearly exhibits the process of lens dehydration.(ABSTRACT TRUNCATED AT 250 WORDS)

Raman spectroscopic evidence for nuclear disulfide in isolated lenses of hyperbaric oxygen-treated guinea pigs

“…Raman spectroscopy has been employed for many years to measure levels of sulfhydryl (-SH) and -SS-in different regions of intact lenses from a variety of species (Askren et al, 1979;Barron et al, 1988;Cai et al, 1989;DeNagel et al, 1988;East et al, 1978;Kuck et al, 1982;Ozaki et al, 1987;Ozaki et al, 1983;Ozaki and Mizuno, 1992;Yu et al, 1985b). The lens is ideal for this type of technique because of its unusually high concentration of both protein (about 35%) and -SH groups (nearly 50mM), and the fact that -SH and -SS-each have their own signature vibrational frequencies at approximately 2577 cm −1 and 503 cm −1 , respectively.…”

Local variations in protein structure in the human eye lens: a Raman microspectroscopic study

“…For quantification of changes in the tryptophan, tyrosine and phenylalanine contents and in the amount of p-sheet conformation, the integrated Raman peaks representing these protein parameters can be related to the CHJCH, vibrations at 1450 cm-'. This peak has been shown to be a reliable protein calibration peak [9,17,181 provided that the proteins do not significantly differ in the number of CH, and CH, groups. On account of the amino-acid composition of human (Y, p and y crystallins given by Coghlan and Augusteyn [19] and the differences in (Y, p and y content between lens cortex and core given by Kramps [20], the calculated number of CH, and CH, groups per 1000 residues was 1650 for the cortex and 1624 for the core; a difference of only 1.6%.…”

“…Conformational protein changes, including dehydration/hydration, formation of aggregates, changes in backbone and side-chains are early signs of increased light scatter, possibly preluding cataract formation. Especially the protein side-chain groups cysteine, tryptophan and tyrosine are thought to play a crucial role in the formation of protein aggregates [8][9][10][11].…”

Biological and Medical Applications of Multivariate Curve Resolution Assisted Raman Spectroscopy

“…Detailed studies by Ozaki group led to a deeper understanding of lens aging and cataract formation through lens hydration, intermolecular disulfide bridge formation and micro environment change of tyrosine residues in lens protein. [56][57][58][59][60][61] Raman spectroscopy has been successfully employed to both in vivo and in vitro, and one can easily find its application in various fields of medicine including pathology, 62,63 physiology, 64 virology, 65 urology, 66,67 and dentistry. [68][69][70] Either by using cells, dissected tissues or real time monitoring during surgery, researchers have demonstrated the utility of Raman spectroscopy, particularly in cancers related to brain, 71,72 83,84 Additionally, by analyzing biofluids such as blood and urine, non-invasive diagnostic assays are also being actively developed for many diseases such as diabetes (glucose level monitoring), 85,86 cancer, 87,88 asthma, 89 and malaria.…”