changes of hGH have a pronounced effect on the retention Interactions of recombinant human growth hormone and lysobehavior in chromatography (3), and for adsorbed LSZ a zyme with solid surfaces are studied using total internal reflection reduction in secondary structure (4, 5) and in enzymatic fluorescence (TIRF) and monitoring the protein's intrinsic tryptoactivity ( ) have been reported. The results of hGH adsorpphan fluorescence. The intensity, spectra, quenching, and polarization are compared with those of the model protein LSZ tion of the fluorescence emitted by the adsorbed proteins are moniwhich has well-characterized physical properties and adsorptored and related to adsorption kinetics, protein conformation, tion behavior (1, 4, 7-9). and fluorophore rotational mobility. To study the influence of elec-Apart from the obvious physiological function of hGH to trostatic and hydrophobic interactions on the adsorption process, regulate cell growth and differentiation (10) the hormone is three sorbent surfaces are used which differ in charge and hydrophobicity. The chemical surface groups are silanol, methyl, and known to regulate the metabolism of lipoproteins and it has quaternary amine. Results indicate that adsorption of hGH is dombeen found that hGH treatment might reduce the risk of inated by hydrophobic interactions. Lysozyme adsoption is cardiovascular diseases ( ). Recently, the application of strongly affected by the ionic strength. This effect is probably hGH in the medical field has been largely broadened due caused by an ionic strength dependent conformational state in to the production of an efficient secretion system for the solution which, in turn, influences the affinity for adsorption. Both recombinant hGH (12). LSZ is found in a variety of verteproteins are more strongly bound to hydrophobic surfaces and this brate cells and secretions, such as spleen, milk, tears, and strong interaction is accompanied by a less compact conformation. egg white. Its natural function is to hydrolyze b glucosidic Furthermore, it was seen that regardless of the characteristics bonds in the proteoglycan layer of bacteria. Both proteins of the sorbent surface, the rotational mobility of both proteins' possess a relatively high structural stability. The rigidity of tryptophans is largely reduced upon adsorption. ᭧ 1997 Academic Press the single-chained lysozyme molecule is imposed by four