This work illustrates the complexity of protein adsorption by ion exchange and hydrophobic interactions and the important role of nonspecific effects in the establishment of the adsorptive process. In ion exchange the interaction mechanism between chymotrypsinogen and lysozyme and two commercially available cation-exchange resins at different pH values and salt concentrations was studied. In hydrophobic interaction, the effect of temperature on the adsorption mechanism of bovine serum albumin onto epoxy-(CH₂)₄-sepharose was analyzed. In both cases observations have been made with respect to the results obtained from flow microcalorimetry. A direct correlation between the heat of adsorption data and isotherm measurements were observed.

Background: Decreased serum concentrations of vitamin B ₁₂ are associated with Alzheimer’s type dementia. The transcobalamin II gene (TCN2) 776C→G polymorphism affects transcobalamin II function as a carrier of vitamin B ₁₂ and might modify its availability. The association of the TCN2 776C→G polymorphism with Alzheimer’s type dementia is unclear and was investigated in the present study. Methods: Case–control study including 27 individuals diagnosed with Alzheimer’s type dementia and 28 healthy controls. Serum concentrations of vitamin B ₁₂ , homocysteine and other analytes were determined and the presence of TCN2 776C→G and 5, 10-methylenetetrahydrofolate reductase 1298A→C polymorphisms genotypes was ascertained by polymerase chain reaction–restriction fragment length polymorphism. Results: Serum concentrations of vitamin B ₁₂ were lower while those of homocysteine were higher in patients than in controls ( P < 0.05). The frequency of individuals carrying at least one 5, 10-methylenetetrahydrofolate reductase 1298C allele was higher (59% versus 32%) while frequency of individuals harbouring at least one TCN2 776G allele was lower (58% versus 86%) in patients than in controls ( P < 0.05). Univariate logistic regression showed negative association of TCN2 776CG genotype with Alzheimer’s type dementia (OR = 0.17 versus CC genotype, P < 0.02). Multivariate logistic regression identified TCN2 776C→G polymorphism as independent predictor of Alzheimer’s type dementia together with higher concentrations of homocysteine, cholesterol and uric acid and lower concentrations of oestradiol. Association of TCN2 776C→G polymorphism with Alzheimer’s type dementia was observed for individuals carrying the 5,10-methylenetetrahydrofolate reductase 1298AA genotype but not the AC or CC genotypes, indicating interaction between the two polymorphisms. Conclusions: The TCN2 776C→G polymorphism is negatively associated with Alzheimer’s type dementia, suggesting a protective role against the disease in subjects with the 5, 10-methylenetetrahydrofolate reductase 1298AA genotype.