Kinesin is the canonical plus-end microtubule motor and has been the focus of intense study since its discovery in 1985. We previously demonstrated a time-dependent inactivation of kinesin in vitro that was fully reversible by the addition of purified casein kinase 2 (CK2) and showed that this inactivation/reactivation pathway was relevant in cells. Here we show that kinesin inactivation result...

Maize (Z ea mays L.) leaf phosphoenolpyruvate (PEP) carboxylase (PEPCase) (EC 4.1.1.31) showed a lag in activity when assayed after storage at 0 4 °C. The lag was prom oted by high pH on storage (7.8 8 .5) and was observed over a range o f assay pH (7.1 -8 .5 ). Therm al reacti­ vation o f the cold-stored enzyme by assay tem perature (18 °C) accounted for most o f the hysteretic effect, but pre...

Formyltetrahydrofolate synthetase undergoes inactivation at pH values below 7. Inactivation is accompanied by both the dissociation of the tetramer into monomers and the exposure of aromatic amino acids to the solvent. The rate of inactivation is a function of pH. This rate and the rate of exposure of tryptophan residues to the aqueous environment follow first order kinetics. After prolonged in...

Long-distance host-independent virus dispersal is poorly understood, especially for viruses found in isolated ecosystems. To demonstrate a possible dispersal mechanism, we show that bacteriophage T4, archaeal virus Sulfolobus spindle-shaped virus Kamchatka, and vaccinia virus are reversibly inactivated by mineralization in silica under conditions similar to volcanic hot springs. In contrast, ba...

The inactivation of lysozyme and ribonuclease by anhydrous formic acid has been shown by Josefsson and Edman (1, 2) to be reversed by adjustment of an aqueous solution of the inactivated enzyme to pH 6.0 to 8.5. Reactivation was accompanied by an uptake of base, approximately equivalent to the number of serine and threonine residues in the proteins. With both proteins an increase in the positiv...

Recent studies on the chemical nature of cytochrome oxidase (cytochrome c :02 oxidoreductase, EC 1.9.3.1) have been concerned largely with the structure of its iron-porphyrin prosthetic group (cj. (l)), the importance of copper as an integral component of the enzyme (e.g. (2-5)), and the possible role of a lipid factor (e.g. (6-8)). By contrast, little work has been done on the nature of the fu...

The tumor suppressor PTEN regulates cell migration, growth, and survival by removing the 3'-phosphate of phosphoinositides. Exposure of purified PTEN or of cells to H(2)O(2) resulted in inactivation of PTEN in a time- and H(2)O(2) concentration-dependent manner. Analysis of various cysteine mutants, including mass spectrometry of tryptic peptides, indicated that the essential Cys(124) residue i...

Because of limitations in the oculomotor range, many gaze shifts must be accomplished using coordinated movements of the eyes and head. Stimulation and recording data have implicated the primate superior colliculus (SC) in the control of these gaze shifts. The precise role of this structure in head movement control, however, is not known. The present study uses reversible inactivation to gain i...

1. The complete inactivation of antistaphylococcal phage by HgCl(2) (2.8 per cent for 216 hours) can be reversed by precipitation of Hg(++) with restoration of the phage to its original titre. 2. This behavior seems more compatible with the known properties of certain enzymes than with those of living protoplasm.

1. The transforming substance of Pneumococcus Type III is inactivated by treatment with ascorbic acid. This effect of ascorbic acid is catalyzed by traces of cupric ion and is prevented by the presence of sulfhydryl compounds. 2. Under certain conditions, the activity of transforming substance treated with ascorbic acid can be restored by the use of glutathione and other sulfhydryl compounds. 3...