kazal pancreatic trypsin inhibitor

Summary

Summary: A secreted KAZAL MOTIF-containing serine peptidase inhibitor that inhibits TRYPSIN. It is a protein composed of 56 amino acid residues and is different in amino acid composition and physiological activity from the Kunitz bovine pancreatic trypsin inhibitor (APROTININ). It protects against the trypsin-mediated premataure activation of ENZYME PRECURSORS in the PANCREAS. Mutations in the SPINK1 gene are associated with CHRONIC PANCREATITIS.

Top Publications

  1. Lee Y, Pan H, Peng S, Lai P, Kuo W, Ou Y, et al. Overexpression of tumour-associated trypsin inhibitor (TATI) enhances tumour growth and is associated with portal vein invasion, early recurrence and a stage-independent prognostic factor of hepatocellular carcinoma. Eur J Cancer. 2007;43:736-44 pubmed
    ..Moreover, it should be possible to use TATI, AFP and osteopontin as combined markers for molecular staging, the detection of HCC and for the prediction of ETR. ..
  2. Paju A, Jacobsen J, Rasmuson T, Stenman U, Ljungberg B. Tumor associated trypsin inhibitor as a prognostic factor in renal cell carcinoma. J Urol. 2001;165:959-62 pubmed
    ..The serum level was an independent prognostic variable. Preoperative serum tumor associated trypsin inhibitor appears to be a useful predictive factor that may be used to identify patients at increased risk of aggressive disease. ..
  3. Wiksten J, Lundin J, Nordling S, Kokkola A, Stenman U, Haglund C. High tissue expression of tumour-associated trypsin inhibitor (TATI) associates with a more favourable prognosis in gastric cancer. Histopathology. 2005;46:380-8 pubmed
    ..022) at the time of surgery were independent prognostic factors. High TATI expression in tumour tissue was detected more frequently in patients with early-stage gastric cancer and seems to correlate with a favourable outcome. ..
  4. Hotakainen K, Bjartell A, Sankila A, Jarvinen R, Paju A, Rintala E, et al. Differential expression of trypsinogen and tumor-associated trypsin inhibitor (TATI) in bladder cancer. Int J Oncol. 2006;28:95-101 pubmed
    ..This may suggest that a balanced expression of TATI and trypsinogen is required in normal tissue and that this balance is disrupted during tumor progression. ..
  5. Marchbank T, Freeman T, Playford R. Human pancreatic secretory trypsin inhibitor. Distribution, actions and possible role in mucosal integrity and repair. Digestion. 1998;59:167-74 pubmed
    ..Further studies including the production of transgenic overexpression and knockout models should help elucidate the physiological function of this peptide. ..
  6. Venesmaa P, Lehtovirta P, Stenman U, Leminen A, Forss M, Ylikorkala O. Tumour-associated trypsin inhibitor (TATI): comparison with CA125 as a preoperative prognostic indicator in advanced ovarian cancer. Br J Cancer. 1994;70:1188-90 pubmed
    ..55-10.68) compared with patients with a smaller or no residual tumour. Thus, preoperative determination of serum TATI may have a place in the pretreatment evaluation of patients with advanced ovarian cancer. ..
  7. Moilanen M, Sorsa T, Stenman M, Nyberg P, Lindy O, Vesterinen J, et al. Tumor-associated trypsinogen-2 (trypsinogen-2) activates procollagenases (MMP-1, -8, -13) and stromelysin-1 (MMP-3) and degrades type I collagen. Biochemistry. 2003;42:5414-20 pubmed
  8. Paju A, Hotakainen K, Cao Y, Laurila T, Gadaleanu V, Hemminki A, et al. Increased expression of tumor-associated trypsin inhibitor, TATI, in prostate cancer and in androgen-independent 22Rv1 cells. Eur Urol. 2007;52:1670-9 pubmed
    ..We demonstrate for the first time that TATI is expressed in the benign and malignant prostate. Increased TATI protein expression is found in high-grade tumors and in 22Rv1 cells in which it is regulated by androgens. ..
  9. Solakidi S, Tiniakos D, Petraki K, Stathopoulos G, Markaki I, Androulakis G, et al. Co-expression of trypsin and tumour-associated trypsin inhibitor (TATI) in colorectal adenocarcinomas. Histol Histopathol. 2003;18:1181-8 pubmed publisher
    ..We conclude that in colorectal neoplasms, high levels of trypsin and TATI may be important for malignant tumour formation and/or metastatic process. ..

More Information

Publications62

  1. Kelloniemi E, Rintala E, Finne P, Stenman U. Tumor-associated trypsin inhibitor as a prognostic factor during follow-up of bladder cancer. Urology. 2003;62:249-53 pubmed
    ..Serum TATI is an independent prognostic factor in transitional cell carcinoma and is potentially useful for the identification of patients with an adverse prognosis. ..
  2. Gouyer V, Fontaine D, Dumont P, De Wever O, Fontayne Devaud H, Leteurtre E, et al. Autocrine induction of invasion and metastasis by tumor-associated trypsin inhibitor in human colon cancer cells. Oncogene. 2008;27:4024-33 pubmed publisher
    ..Targeting TATI, its molecular partners and effectors may bring novel therapeutic applications for high-grade human solid tumors in the digestive and urogenital systems. ..
  3. Schneider A, Pfutzer R, Barmada M, Slivka A, Martin J, Whitcomb D. Limited contribution of the SPINK1 N34S mutation to the risk and severity of alcoholic chronic pancreatitis: a report from the United States. Dig Dis Sci. 2003;48:1110-5 pubmed
    ..The N34S mutation is uncommon in patients with alcoholic chronic pancreatitis in the United States; its prevalence is similar to other countries and appears not to alter the onset or the severity of alcoholic chronic pancreatitis. ..
  4. Tsuzuki S, Miura Y, Fushiki T, Oomori T, Satoh T, Natori Y, et al. Molecular cloning and characterization of genes encoding rat pancreatic cholecystokinin (CCK)-releasing peptide (monitor peptide) and pancreatic secretory trypsin inhibitor (PSTI). Biochim Biophys Acta. 1992;1132:199-202 pubmed
    ..The two genes share extremely high sequence similarity in the 5' flanking regions, suggesting that these regions may be responsible for the characteristic coordinate expression of the two peptides. ..
  5. Keim V, Witt H, Bauer N, Bodeker H, Rosendahl J, Teich N, et al. The course of genetically determined chronic pancreatitis. JOP. 2003;4:146-54 pubmed
    ..The progression of chronic pancreatitis was slightly more rapid in patients with SPINK1 mutations than in patients with cationic trypsinogen mutations, but was much less than in those having alcoholic chronic pancreatitis. ..
  6. Bhatia E, Choudhuri G, Sikora S, Landt O, Kage A, Becker M, et al. Tropical calcific pancreatitis: strong association with SPINK1 trypsin inhibitor mutations. Gastroenterology. 2002;123:1020-5 pubmed
    ..The genetic predisposition to TCP resembles, at least in part, the idiopathic chronic pancreatitis found in industrialized countries. ..
  7. Schneider A. Serine protease inhibitor Kazal type 1 mutations and pancreatitis. Gastroenterol Clin North Am. 2004;33:789-806 pubmed
    ..The most promising candidate gene for such an interaction is the CFTR gene, because genetic alterations within the CFTR gene are also common in the general population and already have been associated with chronic pancreatitis. ..
  8. Diggle C, Cruickshank S, Olsburgh J, Pellegrin S, Smith B, Banks R, et al. Identification of genes up-regulated in urothelial tumors: the 67-kd laminin receptor and tumor-associated trypsin inhibitor. Am J Pathol. 2003;163:493-504 pubmed
  9. Horii A, Tomita N, Yokouchi H, Doi S, Uda K, Ogawa M, et al. On the cDNA's for two types of rat pancreatic secretory trypsin inhibitor. Biochem Biophys Res Commun. 1989;162:151-9 pubmed
    ..Southern blot analyses suggested that both PSTI-I and PSTI-II genes are single copy genes per haploid genome. Duplication of rat PSTI gene seems to have occurred recently, after the divergence of humans and rats. ..
  10. Wittel U, Singh A, Henley B, Andrianifahanana M, Akhter M, Cullen D, et al. Cigarette smoke-induced differential expression of the genes involved in exocrine function of the rat pancreas. Pancreas. 2006;33:364-70 pubmed
    ..Our data show that cigarette smoke exposure leads to an increased vulnerability to pancreatic self-digestion. Moreover, the concomitant involvement of pancreatic ducts occurs only when focal pancreatic inflammation is present. ..
  11. Lukkonen A, Lintula S, von Boguslawski K, Carpen O, Ljungberg B, Landberg G, et al. Tumor-associated trypsin inhibitor in normal and malignant renal tissue and in serum of renal-cell carcinoma patients. Int J Cancer. 1999;83:486-90 pubmed
  12. Hemmi H, Kumazaki T, Yoshizawa Kumagaye K, Nishiuchi Y, Yoshida T, Ohkubo T, et al. Structural and functional study of an Anemonia elastase inhibitor, a "nonclassical" Kazal-type inhibitor from Anemonia sulcata. Biochemistry. 2005;44:9626-36 pubmed
    ..7 A toward the central helix to form the introduced Cys(6)-Cys(31) bond. Such a conformational change in the restricted region correlates with the specificity change of the inhibitor...
  13. Słowińska M, Olczak M, Wojtczak M, Glogowski J, Jankowski J, Watorek W, et al. Isolation, characterization and cDNA sequencing of a Kazal family proteinase inhibitor from seminal plasma of turkey (Meleagris gallopavo). Comp Biochem Physiol B Biochem Mol Biol. 2008;150:207-15 pubmed publisher
    ..The turkey seminal plasma Kazal inhibitor belongs to low molecular mass inhibitors and is characterized by a high value of the equilibrium association constant for inhibitor/trypsin complexes. ..
  14. Uda K, Ogawa M, Shibata T, Murata A, Mori T, Kikuchi N, et al. Purification, characterization and amino-acid sequencing of two pancreatic secretory trypsin inhibitors in rat pancreatic juice. Biol Chem Hoppe Seyler. 1988;369 Suppl:55-61 pubmed
    ..There was no difference in inhibitory properties between PSTI-I and PSTI-II. ..
  15. Tramonti G, Ferdeghini M, Annichiarico C, Donadio C, Norpoth M, Mantuano E, et al. Assessment of tumor-associated trypsin inhibitor (TATI) as a marker of renal function. J Nephrol. 2003;16:663-72 pubmed
    ..When GFR fell, the increase in blood levels of TATI was sooner and higher than that of beta2-microglobulin and CR. Consequently, TATI can be added to the group of renal function markers. ..
  16. Hirota M, Kuwata K, Ohmuraya M, Ogawa M. From acute to chronic pancreatitis: the role of mutations in the pancreatic secretory trypsin inhibitor gene. JOP. 2003;4:83-8 pubmed
    ..These results, along with the brand-new findings in PSTI knockout mice, suggest that the genetic mutation of the PSTI is one of the important mechanisms for predisposition to pancreatitis by lowering the trypsin inhibitory function. ..
  17. Chandak G, Idris M, Reddy D, Mani K, Bhaskar S, Rao G, et al. Absence of PRSS1 mutations and association of SPINK1 trypsin inhibitor mutations in hereditary and non-hereditary chronic pancreatitis. Gut. 2004;53:723-8 pubmed
  18. Liepinsh E, Berndt K, Sillard R, Mutt V, Otting G. Solution structure and dynamics of PEC-60, a protein of the Kazal type inhibitor family, determined by nuclear magnetic resonance spectroscopy. J Mol Biol. 1994;239:137-53 pubmed
  19. Hassan Z, Mohan V, Ali L, Allotey R, Barakat K, Faruque M, et al. SPINK1 is a susceptibility gene for fibrocalculous pancreatic diabetes in subjects from the Indian subcontinent. Am J Hum Genet. 2002;71:964-8 pubmed
    ..02 compared with the ethnically matched control group). These results suggest that the N34S variant of SPINK1 is a susceptibility gene for FCPD in the Indian subcontinent, although, by itself, it is not sufficient to cause disease. ..
  20. Nirmala X, Kodrik D, Zurovec M, Sehnal F. Insect silk contains both a Kunitz-type and a unique Kazal-type proteinase inhibitor. Eur J Biochem. 2001;268:2064-73 pubmed
    ..The structure reveals that the length and arrangement of the B-ring, including exposure of the P1 residue, and the position of the C-terminus relative to the B-loop, are essential for the activity of the Kazal-type inhibitors. ..
  21. Raty S, Sand J, Alfthan H, Haglund C, Nordback I. Cyst fluid tumor-associated trypsin inhibitor may be helpful in the differentiation of cystic pancreatic lesions. J Gastrointest Surg. 2004;8:569-74 pubmed
    ..It appears to be a potential marker in the differential diagnosis of benign from malignant cystic pancreatic lesions. ..
  22. Yi Z, Vitek O, Qasim M, Lu S, Lu W, Ranjbar M, et al. Functional evolution within a protein superfamily. Proteins. 2006;63:697-708 pubmed
  23. Shariat S, Herman M, Casella R, Lotan Y, Karam J, Stenman U. Urinary levels of tumor-associated trypsin inhibitor (TATI) in the detection of transitional cell carcinoma of the urinary bladder. Eur Urol. 2005;48:424-31 pubmed
    ..Urinary level of TATI may add independent information to urinary cytology and NMP22 in the detection of bladder TCC. TATI seems to outperform NMP22 for bladder TCC detection. ..
  24. Stenman M, Ainola M, Valmu L, Bjartell A, Ma G, Stenman U, et al. Trypsin-2 degrades human type II collagen and is expressed and activated in mesenchymally transformed rheumatoid arthritis synovitis tissue. Am J Pathol. 2005;167:1119-24 pubmed
    ..Thus, trypsin-2 and its regulators should be further studied for use as markers of prognosis and disease activity in rheumatoid arthritis. ..
  25. Macdermaid C, Kaminski G. Electrostatic polarization is crucial for reproducing pKa shifts of carboxylic residues in Turkey ovomucoid third domain. J Phys Chem B. 2007;111:9036-44 pubmed
    ..We are confident that our confirmation of the importance of explicit inclusion of polarization in empirical force fields for protein studies will be useful far beyond the immediate goal of accurate calculation of acidity constants. ..
  26. Eriksson U, Hassel J, Lullau E, Häggström L. Metalloproteinase activity is the sole factor responsible for the growth-promoting effect of conditioned medium in Trichoplusia ni insect cell cultures. J Biotechnol. 2005;119:76-86 pubmed
    ..In addition, a gel filtration fraction of CM, eluting at about 10kDa, inhibited cell growth. Apart from a lysozyme precursor protein and a cyclophilin-like protein, a kazal-type proteinase inhibitor could be identified in this fraction. ..
  27. Banfi G, Pirali A, Locatelli M, Murone M, Bonini P. Tumor-associated trypsin inhibitor in induced and acquired immunodeficiency. Studies on transplanted and HIV-infected patients. Scand J Clin Lab Invest Suppl. 1991;207:55-8 pubmed
    ..The increased levels of TATI in immunological disorders suggests its possible use in assessing the immune response against cancer. ..
  28. Aÿ J, Hilpert K, Krauss N, Schneider Mergener J, Hohne W. Structure of a hybrid squash inhibitor in complex with porcine pancreatic elastase at 1.8 A resolution. Acta Crystallogr D Biol Crystallogr. 2003;59:247-54 pubmed
    ..The binding loop of the inhibitor adopts a 'canonical' conformation and the scissile bond Leu-Glu remains intact. ..
  29. Pfützer R, Barmada M, Brunskill A, Finch R, Hart P, Neoptolemos J, et al. SPINK1/PSTI polymorphisms act as disease modifiers in familial and idiopathic chronic pancreatitis. Gastroenterology. 2000;119:615-23 pubmed
    ..Modeling and familial clustering suggest that SPINK1 mutations are disease modifying, possibly by lowering the threshold for pancreatitis from other genetic or environmental factors, but by themselves do not cause disease. ..
  30. Hilpert K, Schneider Mergener J, Aÿ J. Crystallization and preliminary X-ray analysis of the complex of porcine pancreatic elastase and a hybrid squash inhibitor. Acta Crystallogr D Biol Crystallogr. 2002;58:672-4 pubmed
    ..The space group was determined to be P2(1)2(1)2(1), with unit-cell parameters a = 56.33, b = 56.44, c = 72.76 A. A complete X-ray diffraction data set was collected under cryogenic conditions to 1.8 A. ..
  31. Getun I, Brown C, Tulla Puche J, Ohlendorf D, Woodward C, Barany G. Partially folded bovine pancreatic trypsin inhibitor analogues attain fully native structures when co-crystallized with S195A rat trypsin. J Mol Biol. 2008;375:812-23 pubmed
  32. Kato I, Schrode J, Kohr W, Laskowski M. Chicken ovomucoid: determination of its amino acid sequence, determination of the trypsin reactive site, and preparation of all three of its domains. Biochemistry. 1987;26:193-201 pubmed
    ..In the case of the third domain, both the Asn175 glycosylated form, OMCHI3(+), and the carbohydrate-free form, OMCHI3(-), were obtained. These isolated native domains are useful in many studies of ovomucoid behavior. ..
  33. Medl M, Ogris E, Peters Engl C, Leodolter S. TATI (tumour-associated trypsin inhibitor) as a marker of ovarian cancer. Br J Cancer. 1995;71:1051-4 pubmed
    ..It is concluded that, while TATI cannot replace CA 125 in the diagnosis of malignant epithelial carcinomas of the ovaries, it is a valuable additional marker in cases of mucinous carcinomas and in combination with CA 125. ..
  34. Barabote R, Tamang D, Abeywardena S, Fallah N, Fu J, Lio J, et al. Extra domains in secondary transport carriers and channel proteins. Biochim Biophys Acta. 2006;1758:1557-79 pubmed
    ..These studies provide useful information about the evolution of extra domains in channels and secondary carriers and provide novel clues concerning function. ..
  35. Kido H, Yokogoshi Y, Katunuma N. A low-molecular-mass Kazal-type protease inhibitor isolated from rat hepatocytes is identical to rat pancreatic secretory trypsin inhibitor II. Purification and amino acid sequence. Eur J Biochem. 1990;188:501-6 pubmed
    ..Here we report for the first time that PSTI-II is present in other normal tissues besides the pancreas. ..
  36. Santala M, Burger H, Ruokonen A, Stenback F, Kauppila A. Elevated serum inhibin and tumor-associated trypsin inhibitor concentrations in a young woman with dysgerminoma of the ovary. Gynecol Oncol. 1998;71:465-8 pubmed
    ..Inhibin levels correlated closely with disease behavior. In contrast to inhibin, serum TATI and CA 125 failed to reveal the presence of silent disease. ..
  37. Liddle R. Susceptibility to pancreatitis related to PSTI/SPINK1 expression. Gastroenterol Clin North Am. 2004;33:807-16 pubmed
    ..Future studies should clarify the precise molecular interactions between enzymes and inhibitors and how these may be manipulated to prevent or treat pancreatitis. ..
  38. Threadgold J, Greenhalf W, Ellis I, Howes N, Lerch M, Simon P, et al. The N34S mutation of SPINK1 (PSTI) is associated with a familial pattern of idiopathic chronic pancreatitis but does not cause the disease. Gut. 2002;50:675-81 pubmed
    ..Segregation of the N34S mutation in families with pancreatitis is unexplained and points to a complex association between N34S and another putative pancreatitis related gene. ..
  39. Maruyama H, Ogawa M, Nishio T, Kobayashi K, Saheki T, Sunohara N. Citrullinemia type II in a 64-year-old man with fluctuating serum citrulline levels. J Neurol Sci. 2001;182:167-70 pubmed
    ..Even if the serum citrulline level is within the normal range, citrullinemia should be considered in adult patients without primary liver dysfunction who show episodic consciousness disturbance, psychotic symptoms or both. ..
  40. Schneider A, Lawrence E, Barmada M, Norris J, Hamman R, Marshall J, et al. The SPINK1 N34S mutation is not associated with Type 2 diabetes mellitus in a population of the USA. Diabet Med. 2005;22:744-8 pubmed
    ..The SPINK1 N34S mutation appears not to predispose Hispanic or non-Hispanic white people from the USA to the development of Type 2 diabetes mellitus. ..
  41. Witt H, Luck W, Hennies H, Classen M, Kage A, Lass U, et al. Mutations in the gene encoding the serine protease inhibitor, Kazal type 1 are associated with chronic pancreatitis. Nat Genet. 2000;25:213-6 pubmed
    ..In 18 patients, 6 of whom were homozygous, we detected a missense mutation of codon 34 (N34S). We also found four other sequence variants. Our results indicate that mutations in SPINK1 are associated with chronic pancreatitis. ..
  42. Johansen D, Manjer J, Regner S, Lindkvist B. Pre-diagnostic levels of anionic trypsinogen, cationic trypsinogen, and pancreatic secretory trypsin inhibitor in relation to pancreatic cancer risk. Pancreatology. 2010;10:229-37 pubmed publisher
    ..The findings concerning the ratio of HAT/HCT are in line with this. The results related to analyses stratified for other risk factors should be considered as mainly explorative. ..
  43. Ota Y, Masamune A, Inui K, Kume K, Shimosegawa T, Kikuyama M. Phenotypic variability of the homozygous IVS3+2T>C mutation in the serine protease inhibitor Kazal type 1 (SPINK1) gene in patients with chronic pancreatitis. Tohoku J Exp Med. 2010;221:197-201 pubmed
    ..The clinical courses of these patients are apparently different, indicating the phenotypic variability of the SPINK1 IVS3+2T>C mutation-associated CP...
  44. Shibata T, Ogawa M, Takata N, Niinobu T, Uda K, Ukai T, et al. Elevation of serum pancreatic secretory trypsin inhibitor following serious injury. Resuscitation. 1988;16:163-8 pubmed
    ..In contrast, serum PSTI in patients with serious complications remained at high level even at 2 weeks after trauma, and it was not correlated with the initial severity of the injury. ..
  45. Mamathambika B, Bardwell J. Disulfide-linked protein folding pathways. Annu Rev Cell Dev Biol. 2008;24:211-35 pubmed publisher
    ..As a result, the folding pathways of several disulfide-rich proteins are among the best known of any protein. This review discusses disulfide bond formation and its relationship to protein folding in vitro and in vivo. ..
  46. Li Y, Ma W, Dai J, Feng C, Yang F, Ohira T, et al. Inhibition of a novel sperm gelatinase in prawn sperm by the male reproduction-related Kazal-type peptidase inhibitor. Mol Reprod Dev. 2008;75:1327-37 pubmed publisher
    ..The data presented in this study provided evidence that MRPINK has an inhibitory effect on the gelatinolytic activity as well as proteolytic activity of prawn sperm and specifically blocks the activity of MSG. ..
  47. Klaus W, Schomburg D. Solution structure of a variant of human pancreatic secretory trypsin inhibitor determined by nuclear magnetic resonance spectroscopy. J Mol Biol. 1993;229:695-706 pubmed
    ..As the crystal structures of two complexes of human PSTI variants and that of an uncomplexed variant are also known a comparison of the PSTI tertiary structure in solution and in the crystal is now possible. ..
  48. Fukuoka S, Scheele G. Complementary nucleotide sequence for monitor peptide, a novel cholecystokinin-releasing peptide in the rat. Nucleic Acids Res. 1989;17:10111 pubmed
  49. Yamasaki Y, Satomi S, Murai N, Tsuzuki S, Fushiki T. Inhibition of membrane-type serine protease 1/matriptase by natural and synthetic protease inhibitors. J Nutr Sci Vitaminol (Tokyo). 2003;49:27-32 pubmed
    ..The present findings provide important information for the suppression of cancer invasion and metastasis for which MT-SP1/matriptase is responsible. ..
  50. Witt H. The SPINK in chronic pancreatitis: similar finds, different minds. Gut. 2002;50:590-1 pubmed
  51. Graf R, Schiesser M, Bimmler D. Increased secretion of the pancreatic secretory trypsin inhibitor (PSTI-I, monitor peptide) during development of chronic pancreatitis in the WBN/Kob rat. Pancreatology. 2002;2:108-15 pubmed
    ..No evidence for a PSTI mutation was found. Our data does not support the hypothesis that a dysbalance of PSTI/trypsinogen ratio is a causative factor for CP. ..
  52. Grendell J. Genetic factors in pancreatitis. Curr Gastroenterol Rep. 2003;5:105-9 pubmed
  53. Agerberth B, Söderling Barros J, Jornvall H, Chen Z, Ostenson C, Efendic S, et al. Isolation and characterization of a 60-residue intestinal peptide structurally related to the pancreatic secretory type of trypsin inhibitor: influence on insulin secretion. Proc Natl Acad Sci U S A. 1989;86:8590-4 pubmed
    ..The biological role of PEC-60 is not known, but the effect on insulin secretion and the homologies observed suggest important biological activities and interesting structural relationships. ..