Lysozyme absorptivity

These include absorption by adjacent palpebral and bulbar conjunctiva, with concomitant rapid removal from ocular-tissues by peripheral blood flow. For example, the extensive vascularity of the uvea underlies the bulbar conjunctiva, a mucous membrane, and the sclera, a white tissue providing a tough outer covering [177]. Binding of drug to either external sites, like the tear polymers such as mucins or lysozyme, or internal tissues like the sclera can be detrimental to efficacy. 

C.-G. Golander, V. Hlady, K. Caldwell, and J. D. Andrade, Absorption of human lysozyme and adsorbate enzyme activity as quantified by means of total internal reflection fluorescence, 125I labeling and ESCA, Colloids Surf. 50, 113-130 (1990). 

Observations carried out on lysozyme in mixed solvents as a function of temperature demonstrate that lysozyme-catalyzed lysis can he performed under such abnormal conditions and that the reaction can be quenched at subzero temperatures and resumed by heating. The problem is now to check whether one can obtain an enzyme-substrate complex (in this case lysozyme-oligosaccharide) stabilized at low temperature. Such a complex can be detected by differential absorption spectroscopy. Difference spectra in the UV region (240-320 nm) were recorded. The reference cell contained a solution of lysozyme (1.39 x 10 M) and the sample cell contained a solution of lysozyme at the same concentration plus substrate, here hexa-NAG (1.66 x lO " M). The buffer used is acetate at pH 5 plus organic solvent. Also, difference spectra have been determined in the presence of the small-chain sac-... 

An equimolar solution of lysozyme and hexa-NAG, in acetate buffer at pH 4.7 (corresponding to the pH of maximum activity), temperature 20 C, recorded by difference absorption spectrophotometry against a solution of lysozyme (see Fig. 3) shows 3 positive peaks (277, 287, 294 nm) and 2 negative peaks (280, 291 nm). The largest peak (at 294 nm, with a shoulder at 298 nm) occurs during mixing of the enzyme and substrate. This confirms previous results obtained by Hayashi et al. 

Liii and Liv absorb at 280 nm, whereas has no tryptophan or tyrosine residues and shows no absorption at 280 nm, but can be detected with ninhydrin after alkaline hydrolyses. This result reveals that ozone causes the oxidation of the methionine residue 105 of lysozyme. 

Miyake, M., et al. 1984. Rectal absorption of lysozyme and heparin in rabbits in the presence of non-surfactant adjuvants. Chem Pharm Bull 32 2020. 

Nishihata, T., M. Miyake, and A. Kamada. 1984. Study on the mechanism behind adjuvant action of diethylethoxymethylene malonate enhancing the rectal absorption of cefmetazole and lysozyme. J Pharmacobiodyn 7 607. 

Adsorption of the enzymes subtilisin BPN and lysozyme onto model hydrophilic and hydrophobic surfaces was examined using adsorption isotherm experiments, infrared reflection-absorption spectroscopy (IRRAS), and attenuated total reflectance (ATR) infrared (IR) spectroscopy. For both lysozyme and BPN, most of the enzyme adsorbed onto the model surface within ten seconds. Nearly an order-of-magnitude more BPN adsorbed on the hydrophobic Ge surface than the hydrophilic one, while lysozyme adsorbed somewhat more strongly to the hydrophilic Ge surface. No changes in secondary structure were noted for either enzyme. The appearance of carboxylate bands in some of the adsorbed BPN spectra suggests hydrolysis of amide bonds has occurred. 

Figure 2. Measured far-infrared absorption coefficient of dry films of lysozyme...

A useful test for spectrophotometric titrations is to compare the apparent tyrosyl ionization from absorptivity versus pH measurements at several wavelengths. A good illustration is found in Tanford and Wagner s (1954) study on lysozyme. Their measurements at 2880, 2900, and 2950 A resulted in nonidentical titration curves. From these results, they concluded that .. . the observed changes in light absorption are not a true... 

Many of the following studies, particularly those that measure changes by absorption or fluorescence, were made for a-lactalbumin, without corresponding studies on lysozyme that may have been used comparatively. One must consider the likelihood that some such studies have been attempted, but without success, since unsuccessful experiments seldom find their way into the literature. It can only be surmised that the conformational structure of lysozyme is sufficiently more resistant to change that such studies would have proved relatively unproductive. It is well established, in fact, that lysozyme does offer more resistance to denaturative change and to chemical alteration in general (Section 1X,E and F). 

Kronman et al. (1965) and Kronman and Holmes (1965) appear to be the first to have studied the effects of acid on a-lactalbumin and report that this protein, adjusted to pH values below its isoelectric point, exhibits a hypsochromic shift in its absorption spectrum between 270 and 300 nm. Spectral shifts in this region usually reflect changes in the environment of Trp and Tyr residues. The conformational change is a complex one, involving a series of steps. Because of the nature of the shift, the numbers of Trp and Tyr residues present, and the relative magnitudes of e for Trp and Tyr, Kronman and co-workers concluded that the shift results from environmental alterations for more than one of the buried Trp residues. (At the time of this study, three Trp residues were considered to be buried in bovine a-lactalbumin.) There appears to be no corresponding effect for hen egg-white lysozyme. [However, note the effect of acetic acid studied by Kato et al. (1984).]... 

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