Non-neurotoxic plasminogen activating factors for treating of stroke

Abstract

The invention pertains to the use and production of non-neurotoxic plasminogen activating factors e.g. of Desmodus rotundus (DSPA) for the therapeutic treatment of stroke in humans in order to provide a new therapeutic concept for treating stroke in humans.

Description

RELATED APPLICATION [0001] This is a continuation of application Ser. No. 10 / 184,01 filed Jun. 28, 2002, which claims the benefit of priority to German Patent Application No. 101 53 601.1, filed on Nov. 2, 2001, and European Patent Application No. 01 130 006.8 filed on Dec. 17, 2001, all of which are incorporated herein by reference.FIELD OF THE INVENTION [0002] The invention pertains to the therapeutic use of non-neurotoxic plasminogen activators especially from the saliva of Desmodus rotundus (DSPA) preferentially for the treatment of stroke. BACKGROUND OF THE INVENTION [0003] The term “stroke” is a general term that covers conditions having different clinical symptoms. For example, a stroke may be caused by an ischaemic or haemorrhagic insult. [0004] Ischaemic insults (ischaemia) are characterized in a reduction or interruption of the blood circulation in the brain due to a lack of arterial blood supply. Often this is caused by thrombosis of an arteriosclerotic stenosed vessel or...

AI Technical Summary

Benefits of technology

[0037] According to a preferred embodiment of the invention, non-toxic plasminogen activators are used, which comprise at least one element of the so called cymogene triade. A comparable triade is present in the catalytic center of serine proteases of the chymotrypsine family consisting of three interacting amino acids aspartate 194, histidine 40 and serine 32. However, this triade does not exist in t-PA which also belongs to the chymotrypsine family. Nevertheless, it is known, that the directed mutagenesis of native t-PA for the purpose of introducing at least one of the above amino acids at a suitable position results in a reduced activity of the pro-enzyme (single chain t-PA) and in an increased activity of the mature enzyme (double chain t-PA) in the presence of fibrin. Therefore, the introduction of at least one amino acid of the triade—or of an amino acid with the same function in the triade—can increase the cymogenity of t-PA (i.e. the ratio between the activity of the mature enzyme an the activity of the pro-enzyme). As a result the fibrin specificity of t-PA is remarkably increased. This is a result of the conformational interaction between the introduced amino acid residue and / or amino acid residues of the wild type sequence.

[0041] The increase of fibrin specificity of plasminogen activators can alternatively be achieved by a point mutation of Asp194 (or an aspartate at a homologous position). Plasminogen activators belong to the group of serine proteases of the chymotrypsin family and therefore comprise the conserved amino acid Asp194, which is responsible for the stability of the catalytically active conformation of the mature proteases. It is known that Asp194 interacts with His40 in the cymogenic form of serine proteases. After the cymogene is activated by cleavage this specific interaction is interrupted and the side chain of the Asp194 rotates about 170° in order to form a new salt bridge with Ile16. This salt bridge essentially contributes to the stability of the oxyanione pocket of the catalytic center of the mature serine proteases. It is also present in t-PA.

Problems solved by technology

Once in the brain, it activates t-PA that indirectly activates the glutamate receptor or plasminogen, resulting in further tissue damage.

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