Low micromolar zinc accelerates the fibrillization of human tau via bridging of Cys-291 and Cys-322.

A hallmark of a group of neurodegenerative diseases such as Alzheimer disease is the formation of neurofibrillary tangles, which are principally composed of bundles of filaments formed by microtubule-associated protein Tau. Clarifying how natively unstructured Tau protein forms abnormal aggregates is of central importance for elucidating the etiology of these diseases. There is considerable evidence showing that zinc, as an essential element that is highly concentrated in brain, is linked to the development or progression of these diseases.

Binding of calcium ions to Ras promotes Ras guanine nucleotide exchange under emulated physiological conditions.

Both Ras protein and calcium play significant roles in various cellular processes via complex signaling transduction networks. However, it is not well understood whether and how Ca(2+) can directly regulate Ras function. Here we demonstrate by isothermal titration calorimetry that Ca(2+) directly binds to the H-Ras.

Mixed macromolecular crowding accelerates the refolding of rabbit muscle creatine kinase: implications for protein folding in physiological environments.

The effects of four single macromolecular crowding agents, Ficoll 70, dextran 70, polyethylene glycol (PEG) 2000, and calf thymus DNA (CT DNA), and three mixed crowding agents containing both CT DNA and polysaccharide (or PEG 2000) on the refolding of guanidine hydrochloride-denatured rabbit muscle creatine kinase (MM-CK) have been examined by activity assay. When the total concentration of the mixed crowding agent is 100 g/l, in which the weight ratio of CT DNA to Ficoll 70 is 1:9, the refolding yield of MM-CK after refolding for 3 h under these conditions increases 23% compared with that in the presence of 10 g/l CT DNA, 18% compared with 100 g/l Ficoll 70, and 19% compared with that in the absence of crowding agents. A remarkable increase in the refolding yield of MM-CK by a mixed crowding agent containing CT DNA and dextran 70 (or PEG 2000) is also observed.