Matrix metalloproteinase Matrix metalloproteinases
Collectively they are capable of degrading all kinds of
molecules. They are known to be involved in
in/activation. MMPs are also thought to play a major role on cell behaviors such as
. They are distinguished from other endopeptidases by their
s were described by Jermome Gross and Charles Lapiere (1962) who observed
triple helix degradation) during tadpole tail metamorphosis (PMID
he enzyme was named interstitial collagenase (MMP
purified from human skin (1968) (PMID 4967132), and was recognized to be
ption of the "cysteine switch" was described in 1990
Structure
- peptide domain is part of “cysteine switch” this
keeping the enzyme in an inactive form. In the majority of
prohormone convertase cleavage site (Furin
- like) as part of this domain which when cleaved
The catalytic domain
structures of several MMP catalytic domains have shown that this domain
is an oblate sphere measuring 35 x 30 x 30
ed sequence HExxHxxGxxH. Hence, this sequence is a zinc
zinc- binding motif in the catalytic domain (PMID 12486137). The hinge region
The catalytic domain is connected to the C
long, and has no determinable structure. The haemopexin terminal domain
- terminal domain has structural similari
interaction with TIMP’s. The haemopexin
Classification Placing the MMPs in the peptidase families
zinc binding motif (HExxHxxGxxH) in their
turn following the active site. Other mem
Subdivisions of the MMPs
The MMPs can be subdivided in different ways. Use of
MMP - 19; MMPs 11, 14, 15, 16 and 17; MMP
tic domains in isolation suggests that the catalytic domains evolved further
once the major groups had differentiated, as is also indicated by the
. The most commonly used groupings (by researchers in MMP biology) are based partly
on historical assessment of the substrate specificity of the MMP and partly on the
of the MMP. These groups are the collagenases, the gelatinases, the stromelysins,
- MMPs). It is becoming increasingly clear that these divisions
are somewhat artificial as there are a number of MMPs that do not fit into any
Archetypal MMPs The collagenases
These MMPs are capable of degrading triple
capable of degrading them. Traditionally, the collagenases are:
MMP - 18 (Collagenase 4, xcol4, xenopus collagenase.
- MMP) has also been shown to cleave fibrillar
The stromelysins
These enzymes display a broad ability to cleave
. The three canonical members of this group are:
therefore usually associated to convertase
Other MMPs
- 1, occasionally referred to as stromelysin
The matrilysins The gelatinases
distinguished by the presence of an additional domain inserted into the catalytic domain. This
- binding region is positioned immediately before the
does not disrupt the structure of the catalytic domain. The two
Convertase activatable MMPs Secreted
- Was discovered in 2001 and given its name due t
. Contains a threonine in place of proline in its cysteine switch
The membrane bound MMPs
- I transmembrane MMPs 14, 15, 16, 24 (MT1
- peptide, which is a feature also shared by
Function
associated with various physiological and
- 9 are thought to be important in metastasis. MMP
Inhibitors
The MMPs are inhibited by specific endogenous tissue inhibitor of metalloproteinases (TIMPs),
all MMPs are inhibited by TIMPs once they are activated but the gelatinases (MMP
9) can form complexes with TIMPs when the enzymes are in the latent form. The complex of
site tightly. Common chelating groups include
. Hydroxymates are particularly potent inhibitors of MMPs and other zinc
dependent enzymes, due to their bidentate
these inhibitors are usually designed to interact with various binding pockets on the MMP of
interest, making the inhibitor more or less specific for given MMPs. Pharmacology
, at subantimicrobial doses, inhibits MMP activity, and has been used in various
is widely available clinically. It is sold under the trade name
A number of rationally designed MMP inhibitors have shown some promise in the treatment of
MMPs are suspected to be involved in (see above). However, most of these,
- 2516), a broad spectrum MMP inhibitor, and
MMP - 1 selective inhibitor, have performed poorly in
drugs has been largely due to toxicity (particularly musculo
- skeletal toxicity in the case of broad
spectrum inhibitors) and failure to show expected results (in the case of trocade, promising
results in rabbit arthritis models were not replicat
largely disappointing clinical results of MMP inhibitors are
External links
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