Thrombin

Thrombin (EC 3.4.21.5, fibrinogenase, thrombase, thrombofort, topical, thrombin-C, tropostasin, activated blood-coagulation factor II, blood-coagulation factor IIa, factor IIa, E thrombin, beta-thrombin, gamma-thrombin) is a serine protease that in humans is encoded by the F2 gene.Prothrombin (coagulation factor II) is proteolytically cleaved to form thrombin in the coagulation cascade, which ultimately results in the reduction of blood loss. Thrombin in turn acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions.

History

After the description of fibrinogen and fibrin, Alexander Schmidt hypothesised the existence of an enzyme that converts fibrinogen into fibrin in 1872.

Physiology

Synthesis

Thrombin is produced by the enzymatic cleavage of two sites on prothrombin by activated Factor X (Xa). The activity of factor Xa is greatly enhanced by binding to activated Factor V (Va), termed the prothrombinase complex. Prothrombin is produced in the liver and is co-translationally modified in a vitamin K-dependent reaction that converts ten glutamic acids on prothrombin to gamma-carboxyglutamic acid (Gla). In the presence of calcium, the Gla residues promote the binding of prothrombin to phospholipid bilayers. Deficiency of vitamin K or administration of the anticoagulant warfarin inhibits the production of gamma-carboxyglutamic acid residues, slowing the activation of the coagulation cascade.

Factor

Factor, a Latin word meaning "who/which acts", may refer to:

Commerce

Science and technology

Biology

Computer science and information technology

Factor (programming language)

Factor is a stack-oriented programming language created by Slava Pestov. Factor is dynamically typed and has automatic memory management, as well as powerful metaprogramming features. The language has a single implementation featuring a self-hosted optimizing compiler and an interactive development environment. The Factor distribution includes a large standard library.

History

Slava Pestov created Factor in 2003 as a scripting language for a video game. The initial implementation, now referred to as JFactor, was implemented in Java and ran on the Java Virtual Machine. Though the early language resembled modern Factor superficially in terms of syntax, the modern language is very different in practical terms and the current implementation is much faster.

The language has changed significantly over time. Originally, Factor programs centered on manipulating Java objects with Java's reflection capabilities. From the beginning, the design philosophy has been to modify the language to suit programs written in it. As the Factor implementation and standard libraries grew more detailed, the need for certain language features became clear, and they were added. JFactor did not have an object system where you could define your own classes, and early versions of native Factor were the same; the language was similar to Scheme in this way. Today, the object system is a central part of Factor. Other important language features such as tuple classes, combinator inlining, macros, user-defined parsing words and the modern vocabulary system were only added in a piecemeal fashion as their utility became clear.

Factoring (finance)

Factoring is a financial transaction and a type of debtor finance in which a business sells its accounts receivable (i.e., invoices) to a third party (called a factor) at a discount. A business will sometimes factor its receivable assets to meet its present and immediate cash needs.Forfaiting is a factoring arrangement used in international trade finance by exporters who wish to sell their receivables to a forfaiter. Factoring is commonly referred to as accounts receivable factoring, invoice factoring, and sometimes accounts receivable financing. Accounts receivable financing is a term more accurately used to describe a form of asset based lending against accounts receivable.

Factoring is not the same as invoice discounting (which is called an "Assignment of Accounts Receivable" in American accounting – as propagated by FASB within GAAP). Factoring is the sale of receivables, whereas invoice discounting ("assignment of accounts receivable" in American accounting) is a borrowing that involves the use of the accounts receivable assets as collateral for the loan. However, in some other markets, such as the UK, invoice discounting is considered to be a form of factoring, involving the "assignment of receivables", that is included in official factoring statistics. It is therefore also not considered to be borrowing in the UK. In the UK the arrangement is usually confidential in that the debtor is not notified of the assignment of the receivable and the seller of the receivable collects the debt on behalf of the factor. In the UK, the main difference between factoring and invoice discounting is confidentiality.