Matrix metalloproteinases are an important group of zinc enzymes responsible for degradation of the extracellular matrix components such as collagen and proteoglycans in normal embryogenesis and remodeling and in many disease processes such as arthritis, cancer, periodontitis, and osteoporosis. A matrixin family is defined, comprising at least seven members that range in size from Mr 28,000 to 92,000 and are related in gene sequence to collagenase. All family members are secreted as zymogens that lose peptides of about 10,000 daltons upon activation. Latency is due to a conserved cysteine that binds to zinc at the active center. Latency is overcome by physical (chaotropic agents), chemical (HOCl, mercurials), and enzymatic (trypsin, plasmin) treatments that separate the cysteine residue from the zinc. Expression of the metalloproteinases is switched on by a variety of agents acting through regulatory elements of the gene, particularly the AP-1 binding site. A family of protein inhibitors of Mr 28,500 or less binds strongly and stoichiometrically in noncovalent fashion to inhibit members of the family. The serum protein alpha 2-macroglobulin and relatives are also strongly inhibitory.

https://faseb.onlinelibrary.wiley.com/doi/pdf/10.1096/fasebj.5.8.1850705

Matrix metalloproteinases and their inhibitors in connective tissue remodeling.

Matrix metalloproteinases (MMPs) are a family of nine or more highly homologous Zn(++)-endopeptidases that collectively cleave most if not all of the constituents of the extracellular matrix. The present review discusses in detail the primary structures and the overlapping yet distinct substrate specificities of MMPs as well as the mode of activation of the unique MMP precursors. The regulation of MMP activity at the transcriptional level and at the extracellular level (precursor activation, inhibition of activated, mature enzymes) is also discussed. A final segment of the review details the current knowledge of the involvement of MMP in specific developmental or pathological conditions, including human periodontal diseases.

Matrix Metalloproteinases: A Review

基礎講座 電気泳動(Electrophoresis)

Publisher Summary Lectins play an important role in the development of immunology. Lectins also find application in serological laboratories for typing blood and determining secretor status, separating leucocytes from erythrocytes, and agglutinating cells from blood in the preparation of plasma. They serve as reagents for the detection, isolation, and characterization of carbohydrate-containing macromolecules, including blood-group antigens. In their interaction with saccharides, lectins serve as models for carbohydrate-specific antibodies, with the important advantage to purify lectins in gram quantities. Lectins are classified according to their carbohydrate-binding specificity that includes D-mannose(D-glucose)-binding lectins and 2-acetamido-2-deoxy-D-glucose-binding lectins. The chapter considers only those lectins that have been purified to homogeneity, and studied with regard to their biophysical, biochemical, and carbohydrate-binding specificity. The chapter also describes the cell-binding and biological properties of lectins. The chapter concludes with the description of several glycopeptide structures showing the carbohydrate-binding loci with which various lectins interact.

The lectins : carbohydrate-binding proteins of plants and animals

Stress stimulates several adaptive hormonal responses. Prominent among these responses are the secretion of catecholamines from the adrenal medulla, corticosteroids from the adrenal cortex, and adrenocorticotropin from the anterior pituitary. A number of complex interactions are involved in the regulation of these hormones. Glucocorticoids regulate catecholamine biosynthesis in the adrenal medulla and catecholamines stimulate adrenocorticotropin release from the anterior pituitary. In addition, other hormones, including corticotropin-releasing factor, vasoactive intestinal peptide, and arginine vasopressin stimulate while the corticosteroids and somatostatin inhibit adrenocorticotropin secretion. Together these agents appear to determine the complex physiologic responses to a variety of stressors.

https://science.sciencemag.org/content/sci/224/4648/452.full.pdf

Stress hormones: Their interaction and regulation.

In this review, we give an overview of recent literature on the structure and stability of unimolecular G-rich quadruplex structures that are relevant to drug design and for in vivo function The unifying theme in this review is energetics The thermodynamic stability of quadruplexes has not been studied in the same detail as DNA and RNA duplexes, and there are important differences in the balance of forces between these classes of folded oligonucleotides We provide an overview of the principles of stability and where available the experimental data that report on these principles Significant gaps in the literature have been identified, that should be filled by a systematic study of well-defined quadruplexes not only to provide the basic understanding of stability both for design purposes, but also as it relates to in vivo occurrence of quadruplexes Techniques that are commonly applied to the determination of the structure, stability and folding are discussed in terms of information content and limitations Quadruplex structures fold and unfold comparatively slowly, and DNA unwinding events associated with transcription and replication may be operating far from equilibrium The kinetics of formation and resolution of quadruplexes, and methodologies are discussed in the context of stability and their possible biological occurrence

Stability and kinetics of G-quadruplex structures

Cation-induced folding into quadruplex structures for three model human telomeric oligonucleotides, d[AGGG(TTAGGG)3], d[TTGGG(TTAGGG)3A] and d[TTGGG(TTAGGG)3], was characterized by equilibrium titrations with KCl and NaCl and by multiwavelength stopped flow kinetics. Cation binding was cooperative with Hill coefficients of 1.5–2.2 in K+ and 2.4–2.9 in Na+ with half-saturation concentrations of 0.5–1 mM for K+ and 4–13 mM for Na+ depending on the oligonucleotide sequence. Oligonucleotide folding in 50 mM KCl at 25°C consisted of single exponential processes with relaxation times τ of 20–60 ms depending on the sequence. In contrast, folding in100 mM NaCl consisted of three exponentials with τ-values of 40–85 ms, 250–950 ms and 1.5–10.5 s. The folding rate constants approached limiting values with increasing cation concentration; in addition, the rates of folding decreased with increasing temperature over the range 15–45°C. Taken together, these results suggest that folding of G-rich oligonucleotides into quadruplex structures proceeds via kinetically significant intermediates. These intermediates may consist of antiparallel hairpins in rapid equilibrium with less ordered structures. The hairpins may subsequently form nascent G-quartets stabilized by H-bonding and cation binding followed by relatively slow strand rearrangements to form the final completely folded topologies. Fewer kinetic intermediates were evident with K+ than Na+, suggesting a simpler folding pathway in K+ solutions.

Kinetics and mechanism of K+- and Na+-induced folding of models of human telomeric DNA into G-quadruplex structures

Rationale: Markers of inflammatory activity are important for assessment and management of many respiratory diseases. Markers that are currently unrecognized may be more valuable than those presently believed to be useful.Objectives: To identify potential biomarkers of suppurative and inflammatory lung disease in induced sputum samples.Methods: Induced sputum was collected from 20 healthy control subjects, 24 patients with asthma, 24 with chronic obstructive pulmonary disease, 28 with cystic fibrosis (CF), and 19 with bronchiectasis. Twelve patients with CF had sputum sampled before and after antibiotic therapy for an infective exacerbation. The fluid phase of induced sputum was analyzed by surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectroscopy on three protein array surfaces. Some protein markers were selected for identification, and relevant ELISA assays sought. For 12 patients with CF, both SELDI-TOF and ELISA monitored changes in inflammatory responses during infecti...

/pdf/sputum-proteomics-in-inflammatory-and-suppurative-3bd524fi76.pdf

Sputum Proteomics in Inflammatory and Suppurative Respiratory Diseases

The inhibitory potency of four classes of compounds that inhibit corneal ulceration (thiols, tetracyclines, sodium citrate and sodium ascorbate) was assessed with collagenase purified from culture medium of alkali-burned rabbit corneas. The most potent inhibitor, a /3-mercaptomethyl tripeptide HSCH2(Z)L)CHICH2CH(CH3)2]CO-Phe-Ala-NH2, exhibited 50% inhibition (IC50) at -1 0 nM using the synthetic metalloproteinase substrate Dnp-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2. The inhibitor was somewhat less potent with type I collagen as substrate (IC50 between 1 and 3 nM), possibly because autooxidation of the essential —SH moiety of the inhibitor occurred during the longer time required for assay with the natural substrate. An N-carboxyalkyl tripeptide, CH3(CH2)2(DZ,)CH(COOH)-Leu-Phe-Ala-NH2, was less potent (IC50 = 25 nM) than the thiol peptide. N-acetylcysteine, which is used to treat corneal ulceration, gave IC50 values of 2.7 mM and >10 mM with the synthetic and natural substrates, respectively. The IC50 values for the tetracyclines using the synthetic substrate were 15, 190 and 350 MM for doxycycline, minocycline and tetracycline, respectively. Inhibition by sodium citrate, but not the tetracyclines, could be reversed by excess Ca 2+ . Sodium ascorbate did not inhibit collagenase-mediated hydrolysis of either collagen or the synthetic substrate, thus indicating that the mechanism by which this agent inhibits corneal ulceration is not related to inhibition of collagen degradation by collagenase. Invest Ophthalmol Vis Sci 30:1569-1575,1989

Robert D. Gray

Papers

Stability and kinetics of G-quadruplex structures

Kinetics and mechanism of K+- and Na+-induced folding of models of human telomeric DNA into G-quadruplex structures

Sputum Proteomics in Inflammatory and Suppurative Respiratory Diseases

Inhibition of purified collagenase from alkali-burned rabbit corneas.

Folding and unfolding pathways of the human telomeric G-quadruplex.