Analysis of heavy metals in soils, sand, and sewage sludge samples has been studied by means of time-resolved optical emission spectrometry from laser-induced plasma. The instrumental setup has been developed as a fast screening detector
The properties of biomaterials, including their surface microstructural topography and their surface chemistry or surface energy/wettability, affect cellular responses such as cell adhesion, proliferation, and migration. The nanotopography of moderately rough implant surfaces enhances the production of biological mediators in the peri-implant microenvironment with consequent recruitment of differentiating osteogenic cells to the implant surface and stimulates osteogenic maturation. Implant surfaces with moderately rough topography and with high surface energy promote osteogenesis, increase the ratio of bone-to-implant contact, and increase the bonding strength of the bone to the implant at the interface. Certain features of implant surface chemistry are also important in enhancing peri-implant bone wound healing. It is the purpose of this paper to review some of the more important features of titanium implant surfaces which have an impact on osseointegration.
A water insoluble derivative of a papain inhibitor was prepared by covalently linking GlyGly-Tyr(Bz1)-Arg to an agarose resin. The immobilized inhibitor binds active papain specifically. When papain prepared by the method of Kimmel and Smith was activated and applied to a column of the immobilized inhibitor at moderate ionic strength (20 mM EDTA, pH 4.3), about 50 O l 0 of the total protein was not bound and was found to be catalytically inactive. The bound enzyme was released with distilled water. It contained one mole of SH per mole of protein.When assayed with a-N-benzoyl-L-arginine ethyl ester (25", pH 6.0) the purified enzyme had a kcat of 28.5 sec-l and a K , of 18 mM. The specific activity of the p d e d papain was about twice that of the original preparation and the K , was unchanged. The enzyme, inactivated by an equimolar amount of mercuric chloride could be fully activated even after prolonged storage.Crystalline papain as obtained by the method of Kimmel and Smith [I] contains three molecular species : active, activatable and unactivatable papain. The active enzyme represents papain in the thiol form, as judged from the proportionality between thiol content and enzyme activity [2,3]. The activatable papain is mainly an enzyme derivative in which the thiol group is blocked by a cysteinyl residue [4-61. The nature of the unactivatable protein has not yet been established.The maximal SH content of various papain preparations following activation has been found to be 0.5-0.6 moles SH per mole of protein [2,3,, with the notable exception of papain activated by a thioglycolate column where a value of 0.8 moles SH per mole of enzyme was reported [S]. The large proportion of unactivatable protein handicaps studies on the enzyme. Preliminary X-ray diffraction data of papain-inhibitor complexes, for example, suggests low occupancy of inhibitor molecules in the crystal due to the fact that inactive enzyme is incapable of binding competitive inhibitors [9].In the present investigation, a method for the purification of papain by affinity chromatography [lo-151 using a water-insoluble derivative of the papain inhibitor Gly-Gly-Tyr(Bz1)-Arg is described. Some properties of the puriiied enzyme are reported.
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