Αντικείμενο Έρευνας

Το ερευνητικό πρόγραμμα της ομάδας στοχεύει στην κατανόηση των πρωτεϊνών που εμπλέκονται αφ'ενός στο μεταβολισμό του γλυκογόνου (δομή και δράση των ενζύμων φωσφορυλάση του γλυκογόνου και φωσφορυλάση κινάση) και αφ'ετέρου στον έλεγχο της νευρομυικής διαβίβασης (δομή και δράση Fab θραυσμάτων μονοκλωνικών αντισωμάτων (mAbs) που κατευθύνονται προς την κύρια ανοσογόνο περιοχή του νικοτινικού υποδοχέα της ακετυλοχολίνης (AChR)).
Επι μέρους έργα του ερευνητικού προγράμματος είναι:

1. Δομή-Δράση της φωσφορυλάσης του γλυκογόνου (GP).

1.1 Καταλυτικός και αλλοστερικός μηχανισμός.

1.2 Σχεδιασμός εν δυνάμει αντιδιαβητικών φαρμάκων.

2. Δομή-Δράση της φωσφορυλάσης κινάσης.

2.1 Καταλυτικός μηχανισμός.

2.2 Μηχανισμός ενεργοποίησης (απομόνωση και κρυστάλλωση E182S, D149A, Y206F και R148A μεταλλαγμένων ενζυμικών παραγώγων της PhKγtrnc).

3. Αλληλεπιδράσεις αντισώματος:αντιγόνου. Δομή και δράση mAbs έναντι της κύριας ανοσογόνου περιοχής του AChR (σε συνεργασία με τον Δρ. Σωκράτη Τζάρτο, Τμήμα Βιοχημείας του Ελληνικού Ινστιτούτου Pasteur).

Ερευνητικά Χρηματοδοτούμενα Προγράμματα

CHRXERBSC1*CT91-0623: 1991-1994."Interdisciplinary studies on

the control and catalytic mechanism of phosphorylase".

- BMH1-CT93-1100: 1993-1995. "Monoclonal antibodies for

understanding myasthenia gravis and acetylcholine receptor".

- EC Biotechnology Carbohydrate Initiative Contract BIO2CT943025:

1994-1996. "Carbohydrate recognition and control by glycogen

phosphorylase and other enzymes of carbohydrate

metabolism and the design of potential antidiabetic drugs".

- CHRX-CT94-0547: 1994-1996. "Design of high affinity antibody

fragments capable of protecting muscle acetylcholine

receptor: novel therapeutic agents for autoimmune diseases".

- Αναστολείς της γλυκογονικής φωσφορυλάσης ως εν δυνάμει αντιδιαβητικά φάρμακα. ΠΕΝΕΔ-225. Τομέας 3.1. (1996-1998), Υπουργείο Ανάπτυξης, Γενική Γραμματεία Ερευνας & Τεχνολογίας.

- Access to the European synchrotron radiation sources (SRS,

Daresbury, UK; DESY, Hamburg, Germany; ELETTRA, Trieste, Italy)

through grant applications

Επιλεγμένες Δημοσιεύσεις

1. Papageorgiou, A.C., Oikonomakos, N.G., Leonidas, D.D., Bernet, B.,Beer, D., & Vasella, A. (1991). The binding of D-gluconohydroximo-1,5-lactone to glycogen phosphorylase: kinetic, ultracentrifugation and crystallographic studies. Biochem. J. 274,329-338.

2. Leonidas, D.D., Oikonomakos, N.G., & Papageorgiou, A.C. (1991). Sulphate activates phosphorylase b by binding to the Ser (P) site.

Biochim. Biophys. Acta 1076, 305-307.

3. Leonidas, D.D., Oikonomakos, N.G., Papageorgiou, A.C., Acharya, K.R., Barford, D., & Johnson, L.N. (1992). Control of phosphorylase b

by a modified cofactor: Crystallographic studies on R-state glycogen phosphorylase reconstituted with pyridoxal 5'-diphosphate. Protein

Sci. 1, 1112-1122.

4. Leonidas, D.D., Oikonomakos, N.G., Papageorgiou, A.C., & Sotiroudis, T.G. (1992). Kinetic properties of tetrameric glycogen

phosphorylase b in solution and in the crystalline state. Protein Sci. 1, 1123-1132.

5. Oikonomakos, N.G., Acharya, K.R., & Johnson, L.N. (1992). Rabbit muscle glycogen phosphorylase b. The structural basis of activation

and catalysis (review). In Post-Translational Modification of Proteins (Harding, J.J. and Crabbe, M.J.C, eds.), pp. 81-151, CRC Press Inc.,

Boca Raton, Florida.

6. Johnson, L.N., Martin, .L., Acharya, K.R., Barford, D. & Oikonomakos, N.G. (1993). The refined crystal structure of the glycogen phosphorylase-glucose 6-phosphate complex. J. Mol. Biol. 232, 253-267.

7. Vatzaki, E.H., Acharya, K.R., Oikonomakos, N.G. & Tzartos, S.J. (1993). Crystallization and preliminary crystallographic study of an Fab

fragment of a pathogenic rat monoclonal antibody against the nicotinic acetylcholine receptor. Protein Sci. 2, 1770-1772.

8. Watson, K.A., Mitchell, E.P., Johnson, L.N., Son, J.C., Bichard, C.J.F., Orchard, M.G., Fleet, G.W.J., Oikonomakos, N.G., Leonidas,

D.D., Kontou, M. & Papageorgiou, A.C. (1994). Design of inhibitors of glycogen phosphorylase: A study of and -C-glucosides and 1-thio-

-D-glucose compounds. Biochemistry 33, 5745-5758.

9. Watson, K.A., Mitchell, E.P., Johnson, L.N., Cruciani, G., Son, J.C., Bichard, C.J.F., Fleet, G.W.J., Oikonomakos, N.G., Kontou, M. &

Zographos, S.E. (1995). Glucose analogue inhibitors of glycogen phosphorylase: from crystallographic analysis to drug prediction using

GRID force-field and GOLPE variable selection. Acta Crystallogr. D51, 458-472.

10 Bichard, C.J.F., Mitchell, E.P., Wormald, M.R., Watson, K.A., Johnson, L.N., Zographos, S.E., Koutra, D.D., Oikonomakos, N.G. &

Fleet, G.W.J. (1995). Potent inhibition of glycogen phosphorylase by a spirohydantoin of glucopyranose: first pyranose analogues of

hydantocidin. Tetrahedron Lett. 36, 2145-2148.

11. Oikonomakos, N.G., Kontou, M., Zographos, S.E., Watson, K.A., Johnson, L.N., Bichard, C.J.F., Fleet, G.W.J. & Acharya, K.R. (1995).

N-acetyl- -D-glucopyranosylamine: a potent T state inhibitor of glycogen phosphorylase. A comparison with -D-glucose. Protein Sci.

4, 2469-2477.

12. Oikonomakos, N.G., Zographos, S.E., Johnson, L.N., Papageorgiou, A.C. & Acharya, K.R. (1995). The binding of 2-deoxy-glucose-6-phosphate to glycogen phosphorylase b: kinetic and crystallographic studies. J. Mol. Biol. 254, 900-917.

13.Zographos, S.E., Oikonomakos, N.G., Dixon, H.B.F., Griffin, W.G.,Johnson, L.N. & Leonidas, D.D. (1995). Sulphate-activated phosphorylase b : the pH-dependence of catalytic activity. Biochem. J. 310, 565-570.

14.Krulle, T.M., Watson, K.A., Gregoriou, M., Johnson, L.N., Crook, S., Watkin, D.J., Griffiths, R.C., Nasj, R.J., Tsitsanou, A.E., Zographos,

S.E., Oikonomakos, N.G. & Fleet, G.W.J. (1995). Specific inhibition of glycogen phosphorylase by a spirodiketopiperazine at the anomeric

position of glucopyranose. Tetrahedron Lett. 36, 8291-8294.

15. Mitchell, E.P., Withers, S.G., Emert, P., Vasella, A.T., Garman, E.F., Oikonomakos, N.G. & Johnson, L.N. (1996). Ternary complex crystal

structures of glycogen phosphorylase with a transition state analogue nojirimycin tetrazole and phosphate in the T and R states. Biochemistry 35, 7341-7355.

16. Kontou, M., Vatzaki, E.H., Kokla, A., Acharya, K.R., Oikonomakos, N.G. & Tzartos, S.J. (1996). Characterisation, crystallisation and preliminary X-ray diffraction analysis of a Fab fragment of a rat monoclonal antibody with very high affinity for the human muscle acetylcholine receptor. FEBS Lett. 389, 195-198.

17. Bleriot, Y., Smelt, K.H., Cadefau, J., Bollen, M., Stalmans, W., Biggadike, K., Johnson, L.N., Oikonomakos, N.G., Lane, A.L., Crook,

S., Watkin, D.J. & Fleet, G.W.J. (1996). 7- Carbon mimics of D-glucose and L-fucose: Activation by 6R-, and Inactivation by 6S,

6C-Methylglucose of glycogen synthase: Inhibition of Glucokinase and/or Glucose-6-phosphatase. Tetrahedron Lett. 37, 7155-7158.

18. Oikonomakos, N.G., Zographos, S.E., Tsitsanou, K.E., Johnson, L.N. & Acharya, K.R. (1996). Activator anion site in pyridoxal phosphorylase b : The binding of phosphite, phosphate and fluorophosphate anions in the crystal. Protein Sci. 5, 2416-2428.

19 Krulle, T.M., Fuente, C., Watson, K.A., Gregoriou, M., Johnson, L.N., Tsitsanou, K.E., Zographos, S.E., Oikonomakos, N.G. & Fleet, G.W.J. (1997). Stereospecific synthesis of spirohydantoins of -glucopyranose: Inhibitors of glycogen phosphorylase. Synlett., 1997,

211-213.

20. Fuente, C., Krulle, T.M., Watson, K.A., Gregoriou, M., Johnson, L.N., Tsitsanou, K.E., Zographos, S.E., Oikonomakos, N.G. & Fleet,

G.W.J. (1997). Glucopyranose Spirohydantoins: Specific inhibitors of glycogen phosphorylase. Synlett., 1997, 485-487.

21. Lowe, E.D., Noble, M.E.M., Skamnaki, V.T., Oikonomakos, N.G.,Owen, D.J. & Johnson, L.N. (1997). The crystal structure of a

phosphorylase kinase peptide substrate complex: kinase substrate recognition. EMBO J. 16, 6646-6658.

22. Zographos, S.E., Oikonomakos, N.G., Tsitsanou, K.E., Leonidas, D.D., Chrysina, E.D., Skamnaki, V.T., Bischoff, H., Goldman, S.,

Schram, M., Watson, K.A. & Johnson, L.N. (1997). The structure of glycogen phosphorylase b with an alkyl-dihydropyridine-dicarboxylic

acid compound, a novel and potent inhibitor. Structure 5, 1413-1425.

Map.gifΣτερεο-διάγραμμα του τελικού χάρτη (2Fo-Fc) ηλεκτρονικής πυκνότητας για την Τ διαμόρφωση του συμπλόκου φωσφορυλάση b- Bayer W1807 στο αλλοστερικό κέντρο του ενζύμου.