This chapter presents an overview of new developments in vocal exploration. Beginning with a discussion of multiple parameters involved in voice production, this chapter identifies the crucial role that non-linear phenomena has in the performance of the extra-normal voice. In this article, two related taxonomies are presented (source production related to degree of voicing; emphases within the aco

The facile synthesis of esters by lipase-catalysed esterification of fatty acids and ethanol is demonstrated. Evaporation of the water generated in the reaction allowed the rapid production of esters of >99% yield in refluxing pentane or hexane. Water was trapped by condensing the refluxing vapor phase and passing it over activated molecular sieves in a reflux trap. High yields were rapidly obtain

In α-chymotrypsin-catalyzed acyl-transfer reactions in water the specificity of the enzyme (the nucleophile reactivity of amino acid amides) is correlated with the substrate hydrophobicity and increases as the hydrophobicity of the side chain of the amino acid amides is increased. In a low water system (4% H2O) bulky amino acid amides are less efficient nucleophiles. The specificity of α-chymotryp

Nucleophilic properties of amino-acids were studied systematically in acyl-transfer reactions catalyzed by α-chymotrypsin and subtilisin from Bacillus subtilis strain 72 (subtilisin 72) using Mal-l-Ala-l-Ala-l-PheOMe as the acyl-group donor. In α-chymotrypsin-catalyzed reactions, the nucleophile reactivities increase in the following order: d-AlaNH2 < GlyNH2 < l-AlaNH2 < l-ScrNH2 < l-ThrNH2 < l-Hi

Enzyme catalysis in water-immiscible organic solvents is strongly influenced by the amount of water present in the reaction mixture. Effects of substitution of part of the water by other polar solvents were studied. In an alcoholysis reaction catalyzed by chymotrypsin deposited on celite, it was possible to exchange half of the water by formamide, ethylene glycol or dimethyl sulfoxide with often i

Chymotryspin and ethyl cellulose were mixed in an aqueous phosphate buffer solution and freeze dried. Due to complex formation between the substances it was possible to dissolve or at least finely disperse these preparations in toluene. The chymotrypsin-ethyl cellulose complexes were characterized by light scattering measurements. Complexes were also formed by mixing enzyme powder in toluene conta

A model system consisting of pure triolein and palmitic acid and LipozymeTM, an immobilized lipase (E.C. 3.1.1.3.). has been used to determine the effects of various reaction parameters on the reaction rate and the formation of by-products in the interesterification reaction. The goal was to minimize the level of diglycerides and eliminate trisaturated triglycerides at an endpoint chosen so that t

Biocatalytic systems using enzymes in organic solvents open up the possibility of performing a whole range of reactions which would not normally occur under physiological conditions. The ability to perform reverse hydrolysis, or to convert substances relatively insoluble in aqueous environments on a scale of practical value in commercial applications are among those reactions for which water-poor

Gluconobacter oxydans (ATCC 621) were permeabilized with toluene and then lyophilized. This crude enzyme preparation was used to reduce eleven ketones to (S)-alcohols with high enantiomeric excess (for most alcohols 93%-99% e.e.). The coenzyme NADH was regenerated either by adding a second enzyme, formate dehydrogenase, and its substrate, formate, or with 2-butanol as a second substrate for the G.

11 amino acid derivatives were tested as α-chymotrypsin substrates in the esterification reaction with methanol in organic media. The reactions were carried out in water-saturated ethyl acetate and in acetonitrile containing 4% water. α-Chymotrypsin adsorbed on Celite was used as a catalyst. From initial reaction rate measurements, the Michaelis-Menten parameters Vmax and KM were determine. All th

Six strains of acetic acid bacteria were evaluated with respect to their capability to catalyze the stereoselective reduction of ketones. The cells were permeabilized before the bioconversions. The best strains were Gluconobacter oxydans DSM 50049 and Acetobacter aceti DSM 2002. Using either of these two strains it was possible to reduce all 12 ketones to (S)-alcohols with an enantiomeric excess o

Enzymes were deposited on different porous support materials and these preparations were used to catalyze reactions in organic media. Reactions were carried out at specific water activities, achieved by equilibrating both the enzyme preparation and the substrate solution at the desired water activity before mixing them and thereby starting the reactions. The reaction rates obtained at the same wat