This disclosure relates to a method of generating conditionally active biologic proteins from wild type proteins, in particular therapeutic proteins, which are reversibly or irreversibly inactivated at the wild type normal physiological conditions. For example, evolved proteins are virtually inactive at body temperature, but are active at lower temperatures.

This disclosure relates to a method of generating conditionally active biologic proteins from wild type proteins, in particular therapeutic proteins, which are reversibly or irreversibly inactivated at the wild type normal physiological conditions. For example, evolved proteins are virtually inactive at body temperature, but are active at lower temperatures.

Disclosed herein is a protein purification system and methods of using the system. In particular, disclosed is a split intein comprising an N-terminal intein segment, which can be immobilized, and a C-terminal intent segment, which has the property of being self-cleaving, and which can be attached to a protein of interest. Through the self-cleaving mechanism of the intein, the protein of interest can be purified.

Disclosed herein is a protein purification system and methods of using the system. In particular, disclosed is a split intein comprising an N-terminal intein segment, which can be immobilized, and a C-terminal intein segment, which has the property of being self-cleaving, and which can be attached to a protein of interest. Through the self-cleaving mechanism of the intein, the protein of interest can be purified.

Disclosed herein is an expression system for the production and secretion of biologically active clot-specific streptokinase (CSSK) protein in methylotrophic yeast. Yeast-expressed CSSK protein displays improved plasminogen activation and fibrin selectivity. Further disclosed are methylotrophic yeast transformed with at least one copy of functional cDNA sequence encoding CSSK adjunct with modified signal sequence which results in secretion of mature and correctly processed CSSK.

Disclosed herein is a protein purification system and methods of using the system. In particular, disclosed is a split intein comprising an N-terminal intein segment, which can be immobilized, and a C-terminal intein segment, which has the property of being self-cleaving, and which can be attached to a protein of interest. Through the self-cleaving mechanism of the intein, the protein of interest can be purified.

This disclosure relates to a method of generating conditionally active biologic proteins from wild type proteins, in particular therapeutic proteins, which are reversibly or irreversibly inactivated at the wild type normal physiological conditions. For example, evolved proteins are virtually inactive at body temperature, but are active at lower temperatures.

This disclosure relates to a method of generating conditionally active biologic proteins from wild type proteins, in particular therapeutic proteins, which are reversibly or irreversibly inactivated at the wild type normal physiological conditions. For example, evolved proteins are virtually inactive at body temperature, but are active at lower temperatures.

This disclosure relates to a method of generating conditionally active biologic proteins from wild type proteins, in particular therapeutic proteins, which are reversibly or irreversibly inactivated at the wild type normal physiological conditions. For example, evolved proteins are virtually inactive at body temperature, but are active at lower temperatures.

The present invention relates to novel mutants of Streptokinase, its functional fragments and covalently modified forms. Methods are provided for the preparation of the bacterial plasminogen activator protein, Streptokinase its muteins, species variants and their covalently modified variants that are characterized by improved therapeutic properties, such as increased proteolytic stability, extended plasma half-lives, reduced immuno-reactivity and enhanced fibrin clot specificity. The method involves either incorporating additional cysteine residues, or substituting cysteine residues for naturally occurring amino acids into non-essential regions of the protein such that the catalytic activity of the resultant protein remains largely unaltered. These cysteine variants were further modified by covalently attaching a cysteine reactive polymer such as polyethylene glycol (PEG) or sulfhydryl-reactive moieties from a group that includes fluorophore, spin labels or other small conjugates. Disclosed herein are site-specific biologically active conjugates of Streptokinases and its covalently modified variants.