Enzymatic activity, locations used

Membranes contain many proteins, some of which have enzymatic activity. Some of these enzymes are located only in certain membranes and can therefore be used as markers to follow the purification of these membranes. 

The second main class of blood constituents used as genetic markers are the polymorphic enzymes. The enzymes of interest to the forensic serologist are primarily located within the red blood cell and are commonly referred to as isoenzymes. These can briefly be described as those enzymatically active proteins which catalyze the same biochemical reactions and occur in the same species but differ in certain of their physicochemical properties. (This description does not exclude the tissue isoenzymes that occur within the same organism however, our consideration deals only with those of the red blood cell in particular.) The occurrence of multi-molecular forms of the same enzyme (isoenzymes) has been known for several decades however, it was not until the Metropolitan Police Laboratory of Scotland Yard adapted electrophoretic techniques to dried blood analysis that these systems were catapulted to the prominence they presently receive (.2). For many of the forensic serologists in the United States, the use of electrophoresis and isoenzyme determination is a recently-inherited capability shared by only a few laboratories. 

Q.24.16 What three locations can be used to control enzymatic activity ... 

Electrocatalysis is an important application of electron-induced processes. In electrocatalysis the catalyst has at first to accept chaige(s) from the electrode, and thereafter catalysis can take place. Enzyme-immobilized electrodes are tj ical examples used for various biosensors as well as for investigation of fundamental biocatalysis. The enzymatic active center is often located inside a protein molecule, so that mediation of charges from the electrode surface to the active center is important. Viologens, metallocenes and other metal complexes have been used as such mediators. 

HLADH contains two zinc ions per subunit. One of the zinc ions is called the "catalytic zinc" and is located in the active site of the enzyme (Sigman 1967). The catalytic zinc can be specifically depleted with concomitant loss of enzymatic activity or substituted by other metal ions with distinctly reconstituted activities. The enzyme is strongly inhibited by metal chelating agents such as pyrazole, which has been well exploited by studies of the reaction mechanism (McFarland and Bernhard 1972, Schmidt et al. 1979). The other zinc ion, the "structural zinc", is used to maintain the three-dimensional structure of the enzyme. 

The amino acid sequences of the purified pig pantetheinase protein (Maras et al. 1999) revealed that the amino acid sequences of mouse vanin-1 and human VNN-1 are quite similar to that of pig pantetheinase. In addition, recombinant proteins made from both mouse vanin-1 and human VNN-1 cDNAs have pantetheinase enzymatic activity (Pitari et al. 2000), confirming that the mouse vanin-1 and the human VNN-1 are homologues of the pig pantetheinase. Mouse pantetheinase/vanin-1 is produced as a glycosylpho-sphatidyl inositol (GPI)-anchored protein and is located on the plasma membrane of epithelial cells. The role of mouse vanin-1 is well documented using vanin-1-deficient mice (see below). 

Attempts are made to localize certain enzymatic activities in various parts of the inner membrane. The 90 A knobs have bera isolated they contain one of the coupling factors Ft in Racker s terminology). It is possible to obtain from mitochondria sealed vesicles which are either correctly oriented or turned indde out (Fig. 7) using the 90 A knobs as markers for the matrix side, it has been possible to conclude that cytochrome c is located at. or bound from, the outer side of the inner membrane. 

---