The influence of water on the glucose affinity of hexokinase

In the present thesis, the role of hydration during the glucose induced conformational change of hexokinase is investigated. This is accomplished by applying the osmotic stress technique. The osmotic stress technique is founded on varying of the activity of water in a system in order to determine ifs effects. This is accomplished by adding inert solute molecules that are excluded from the system under study. The solute molecules used within the present investigation are Polyethylene glycols (PEGs). PEGs aid in the removal of water from hexokinase by exerting osmotic pressure. The osmotic pressures of the PEG solutions are also measured with both vapour pressure osmometry and secondary osmometry with phospholipids. An interesting discovery is made in that the osmotic pressures of PEG and co-solute solutions are non-additive. This indicates that PEG concentrates co-solutes in solution by making a certain proportion of the water inaccessible. Glucose binding was measured fluorometrically and the glucose equilibrium dissociation constant (GEDC) of hexokinase is measured in solutions containing the different MW PEGs. Changes in the sensitivity of the glucose affinity with osmotic pressure allows the calculation of the change in the numbers of polymer-inaccessible water molecules upon the binding of glucose to hexokinase ~Nw. It was determined the ~Nw decreases with increases in osmotic pressure in the presence of all MW PEGs. ~Nw decreases from values between 45-290 water molecules at low pressure to approximately 15 at high pressure. There is also a molecular weight dependence observed. There are large decreases in ~Nw with osmotic pressure in the presence of PEGs above MW 1000. However, below MW 1500 changes in ~Nw with osmotic pressure are relatively small. These findings are interpreted with respect to two possible mechanisms involving changes in the conformation of hexokinase u~der osmotic pressure and the access of the PEG molecules to water surrounding hexokinase.

Canadian Beer Labels

An assortment of Canadian beer labels.

Imported Brandy Labels

A selection of Brandy labels all imported by the Liquor Control Boards. One is an import from Portugal for the Liquor Control Board of British Columbia, the other imports are for the Liquor Control Board of Ontario and are from France, Portugal, and South Africa.

Sir Robert Burnett Labels

A collection of Sir Robert Burnett labels. The company was established in England in 1770, but these labels read "Distilled and Bottled according to the Original Formula of Sir Robert Burnett Co., Ltd. London W.I., England by The Sir Robert Burnett Co. A Division of Distillers Corporation Ltd. Montreal, Canada".

Gooderham's Labels

A collection of Gooderham's labels that include: Bonded Stock Canadian Whisky, London Dry Gin, Big Brown Jug Canadian Rye Whiskey, and Rich and Rare Canadian Whiskey. The labels indicate the distillery was established in 1832, Toronto, and is Canada's first.

Hiram Walker Labels

Six labels from the Hiram Walker Company, established 1858. The labels are from Gold Crest Canadian Whiskey, Crystal London Dry Gin, Peppermint Schnapps Liqueur, Creme de Menthe, Crystal Vodka Distilled, and Canadian Club Canadian Whiskey.

Central Europe Labels

A selection of European alcohol labels, including: Grandezza Dansk Frugivinsfabrikat, Max and Moritz Perlwein, Gumpoldskirchner Konigswein Neuburger, Jisenski Biser.