- CROSS-LINKED COMPOSITIONS
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Improved compositions comprising a cross-linkable protein or polypeptide, and a non-toxic material which induces cross-linking of the cross-linkable protein. The compositions are optionally and preferably prepared in a non-phosphate buffer solvent. Optionally and preferably, the cross-linkable protein includes gelatin and any gelatin variant or variant protein as described herein. Optionally and preferably, the non-toxic material comprises transglutaminase (TG), which may optionally comprise any type of calcium dependent or independent transglutaminase, which may for example optionally be a microbial transglutaminase (mTG).
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- Kinetics and mechanism of alkaline hydrolysis of urea and sodium cyanate
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The kinetics of hydrolysis of urea has been studied in 0.5 to 3.0 mol dm-3 sodium hydroxide solution at different temperatures. Urea hydrolysis follows an irreversible first order consecutive reaction path: equation presented The variation of Klobs with [alkali] is linear at [OH-] = 5.0 to 1.5 mol dm-3, thereafter a sharp increase in the reaction rate is observed for first step hydrolysis of urea. The second step rate constant (K2obs) is found to be independent of [alkali]. Hydrolysis of urea in alkaline medium follows an elemination-addition mechanism. The reaction does not proceed through the formation and decomposition of tetrahedral intermediate. Sodium cyanate hydrolysis obeys an irreversible pseudo-first order kinetics. [OH-] has no significant effect on the rate constants. The following rate equations have been derived for the two step hydrolysis of urea. Klobs = K0 + K1[OH-](K4 + K3[OH-])/K-1 + K4 + K3[OH-] K2obs = K2Kh On the basis of observed data, probable mechanisms have been proposed.
- Khan, Zaheer,Rafiquee,Kabir-ud-din,Arif Niaz,Aziz Khan
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p. 1116 - 1119
(2007/10/03)
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- REACTION OF UREA WITH ALKALI-METAL CARBONATES. II. EFFECT OF REACTION CONDITIONS ON SELECTIVITY OF THE PROCESS
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The dependence of the composition of the reaction mixture on time was determined during the reaction of urea with alkali-metal carbonates under isothermal conditions.At temperatures up to 150 deg C the cyanates and allophanates of the respective metals are formed as a result of conjugate reactions, and the reaction rate increases with increase in the radius of the metal cation.An increase in the selectivity for the production of the cyanates is secured by the presence of urea in the reaction mass throughout the process.
- Karachinskii, S. V.,Gazizov, R. R.,Dragalov, V. V.,Chimishkyan, A. L.
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p. 1265 - 1268
(2007/10/02)
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