PATENT ABSTRACTS 103

An improved process for purifying proteins, particularly proteins having molecular weights in excess of 12,000 involves novel applications of high performance liquid chromatography on a preparative scale to provide homogeneous end product in excellent yield. In an embodiment of the process, human interferon is produced as a homogeneous protein.

4503142

Measurement of the fluorescence is based on the principle of measurement of the frequency at which the emission maximum occurs. A fluores- cent substance suitable for this purpose is 2,3- dicyano- 1,4-hydroquinone. A suitable membrane penetrating compound is 1,4- diacetoxy-2,3-dicyanobenzene or 1, 4- dibutyryloxy-2,3-dicyanobenzene or 1, 4-di(- tert-butyloxycarbonyl- 1 -alanyloxy)-2,3- dicyanobenzene.

O P E N R E A D I N G F R A M E V E C T O R S

Michael Berman, Thomas Silhavy, George M Weinstock assigned to Litton Bionetics Inc

An open reading frame DNA vector is presented having a promoter-translation start region, and adjacent thereto and downstream therefrom, a first coding segment having a start codon, a second coding segment coding for detectable protein, and an insertion region between said first and second coding regions having an inser- tion site and being of such length that the first and second coding segments are not in reading frame phase with each other. A method for the Cloning and positive selection ofa DNA segment having an open reading frame is also presented, as well as a tribrid protein wherein each terminal region and the mid-section is derived from a dif- ferent gene, and a method of identifying and quantifying a protein or polypeptide without regard to its structure or biological function by using a DNA segment coding for said protein or polypeptide as the mid-section of the tribrid pro- tein.

4504413

A C E T A M I N O P H E N A N A L O G S , A N T I G E N S , A N D A N T I B O D I E S

Pyar Khanna assigned to Syva Company

H ° - - ~ N H - - C O - - X ]~ z

Carbonyl derivatives of acetaminophen are pro- vided for use in homogeneous enzyme immuno- assays for acetaminophen. The derivatives are conjugated to antigenic substances for the pre- paration of antisera specific to acetaminophen, and to enzymes for the preparation of enzyme conjugates which compete with acetaminophen for antibody binding sites in a typical assay.

4505756

A L P H A - A M Y L A S E A S S A Y A N D S U B S T R A T E S F O R U S E T H E R E I N

4503148

P R O C E S S F O R D E T E R M I N I N G T H E P H V A L U E I N T H E

I N T E R I O R O F A C E L L

Gunter Vale t, Gerhard Ruhenstroth-Bauer, Erich Wunsch, Luis Moroder, D 8000 Mfederal Republic Of Germana

A process for determining the pH value in the interior of a cell is described. This is ac- complished by measurement of the emission of a fluorescent substance which is absorbed by the cell through incubation in a solution. The solu- tion contains a compound of the said fluorescent substance; the fluorescent substance is separated from this compound in the cell by an enzyme pre- sent in the cell. The fluorescent substance selec- ted is one such that the frequency of the emission maximum is dependent on the pH value. The compound of this fluorescent substance which is selected is one which is membrane penetrating.

Paul T Nix, Rebecca D Goldfarb, Linda J Stong, Lorraine E Sulick, Ramesh C Trivedi, Stanley Morgenstern assigned to CooperBiomedical Inc

A maltodextrin phosphorylase limit dextrin in the presence of maltodextrin phosphorylase and inorganic phosphate, is used as a substrate for alpha-amylase, which initiates a series of en- zymatic reactions resulting in a chromogen response which can be used to measure the con- centration of alpha-amylase in a body fluid. A novel limit dextrin and its preparation also are described.

4506010

M E T H O D F O R T E S T I N G M I C R O B I A L D E G R A D A T I O N O F

C E L L U L O S E

Nelson Goodman, Brian C Cunningham as- signed to Stauffer Chemical Company

104 PATENT ABSTRACTS

Changes in the optical density and viscosity measurements of a water-soluble cellulose derivative which is enzyme depolymerizable can be used as a method to determine growth of

cellulase-producing microorganisms and cel- lulose degradation. The method is particularly well suited to the measurement of the effect of pesticides on cellulose degradation.