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Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 169-175).

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [173]-180).

Follicle stimulating hormone (FSH) comprises an ?? subunit and a ?? subunit,whereas the FSH receptor consists of two halves with distinct functions, the N-terminalextracellular exodomain and C-terminal membrane associated endodomain. FSH initiallybinds to exodomain, and the resulting FSH/exodomain complex modulates the endodomainand generates signal. However, it has been difficult to determine which subunit of FSHcontacts the exodomain or endodomain, and in what orientation FSH interacts with them.To address these crucial issues, the receptor was Ala-scanned and the hormone subunitswere probed with photoaffinity labeling with receptor peptides corresponding to the Nterminalregion of the exodomain and exoloop 3 of the endodomain. The results show thatboth regions of the receptors are important for hormone binding and signal generation. Inaddition, the FSH ?? subunit is specifically labeled with the N-terminal peptide, whereas the?? subunit is labeled with the exoloop 3 peptide. These contrasting results show that the FSH?? subunit is close to the N-terminal region and the ?? subunit is projected toward exoloop 3in the endodomain. The results raise the fundamental question whether the ?? subunit,common among the glycoprotein hormones, plays a major role in generating the hormonesignal common to all glycoprotein hormones.

The luteinizing hormone / choriogonadotropin receptor (LH/CG-R) is a member of theG protein-coupled receptor family. The LH/CG-R has seven transmembrane helices, threeexoloops, three cytoloops, a C-terminal tail, and an extensive N-terminal exodomain. Theexodomain is capable of binding hormone with high affinity without hormone action. Previousstudies have shown that the amino-terminal region of the LH/CG receptor contacts both subunitsof human chorionic gonadotropin (hCG). In particular, three residues (Leu20, Cys22, and Gly24)were found to be crucial for hormone binding. In this thesis work, benzoylphenylalanine (Bpa),a photoactivatable reagent, was used to continue investigating the interactions of the N-terminalregion of the LH/CG-R with hCG. Bpa has been directly incorporated at a defined position intopeptides representing amino acids 17-36 of the LH/CG-R. These peptides were radiolabeledwith 125I and used in photoaffinity labeling studies to identify and characterize the contact site(s)between the N-terminal region of the LH/CG-R and hCG. Results suggest that Cys22 is theprimary contact residue in this region. Peptide and hormone concentration dependent as well asUV duration dependent photoaffinity labeling experiments confirm that the photolabeling ofhCG by hLHR17-36(C22Bpa) is specific. Competition of labeling studies indicate that the hLHR17-36(C22Bpa) peptide is a good mimic of the wild type N-terminal portion of the receptor. In-geldigestions of photolabeled hCG ?? and photolabeled hCG ?? with CNBr indicate that the Nterminalregions of both hCG ?? and hCG ?? were photoaffinity labeled by hLHR17-36(C22Bpa).Based on the fact that the N-terminal regions of each subunit are located on the convex side ofthe heterodimer, these results provide evidence that the N-terminal portion of the receptor wrapsaround the back of hCG, contacting the convex face of the hormone.

Steroid sulfatase (STS) is considered to be one of the key enzymes contributing to the development of breast cancer. It catalyzes the hydrolysis of inactive sulfated steroids such as estrone sulfate (ES) to inorganic sulfate active steroids such as estrone (E1), a precursor to estradiol (E2), a key stimulator for breast cancer development. Inhibitors of STS are currently being pursued in both academia and industry as potential drugs for treating breast cancer. A series of 4-substituted estrone and estradiol derivatives were examined as inhibitors of STS. Inhibition of STS with 4-FE1, an irreversible inhibitor of STS previously studied in the Taylor group, can be enhanced by introducing a hydrophobic benzyl group at the 17-positon of 4-FE1. As with 4-FE1, the inhibition was concentration and time-dependent. Only 14% of the activity could be recovered after extensive dialysis. Introducing substituents at the 2-position of 4-formyl estrogen derivatives resulted in loss of concentration and time-dependent inhibition and a considerable decrease in inhibitor affinity. Studies with estrogen derivatives substituted at the 4-position with groups other than a formyl revealed that a relatively good reversible inhibitor can be obtained simply by introducing an electron withdrawing group at this position. These types of inhibitors are non-competitive inhibitors suggesting an alternative steroid binding site. A series of estrone derivatives were examined as photoaffinity labels of STS. 4-azidoestrone suflate and 4-azidoestrone phosphate exhibited properties that are suitable for photoaffinity labeling studies with STS. These labels may be useful for ascertaining pathways of substrate entry into the STS active site. 16-diazoestrone phosphate was not a photoaffinity label of STS. 2- and 4-azido estrone and 16-diazoestrone all acted as photoaffinity labels of STS. These compounds may be useful for ascertaining pathways of product release from the STS active site.

Steroid sulfatase (STS) is considered to be one of the key enzymes contributing to the development of breast cancer. It catalyzes the hydrolysis of inactive sulfated steroids such as estrone sulfate (ES) to inorganic sulfate active steroids such as estrone (E1), a precursor to estradiol (E2), a key stimulator for breast cancer development. Inhibitors of STS are currently being pursued in both academia and industry as potential drugs for treating breast cancer. A series of 4-substituted estrone and estradiol derivatives were examined as inhibitors of STS. Inhibition of STS with 4-FE1, an irreversible inhibitor of STS previously studied in the Taylor group, can be enhanced by introducing a hydrophobic benzyl group at the 17-positon of 4-FE1. As with 4-FE1, the inhibition was concentration and time-dependent. Only 14% of the activity could be recovered after extensive dialysis. Introducing substituents at the 2-position of 4-formyl estrogen derivatives resulted in loss of concentration and time-dependent inhibition and a considerable decrease in inhibitor affinity. Studies with estrogen derivatives substituted at the 4-position with groups other than a formyl revealed that a relatively good reversible inhibitor can be obtained simply by introducing an electron withdrawing group at this position. These types of inhibitors are non-competitive inhibitors suggesting an alternative steroid binding site. A series of estrone derivatives were examined as photoaffinity labels of STS. 4-azidoestrone suflate and 4-azidoestrone phosphate exhibited properties that are suitable for photoaffinity labeling studies with STS. These labels may be useful for ascertaining pathways of substrate entry into the STS active site. 16-diazoestrone phosphate was not a photoaffinity label of STS. 2- and 4-azido estrone and 16-diazoestrone all acted as photoaffinity labels of STS. These compounds may be useful for ascertaining pathways of product release from the STS active site.

The luteinizing hormone receptor (LHR) belongs to the G protein-coupled receptorfamily. It consists of two distinct domains; the N-terminal extracellular exodomain and themembrane associated endodomain which includes 7 transmembrane domains, 3 exoloops, 3cytoloops and a C-terminal tail. Sequence alignment and computer modeling suggest thepresence of Leu Rich Repeat (LRR) motifs in the exodomain. Although their structuralsimilarity is high, each LRR is not equally important for hormone binding. Ala-scanning andtruncation studies performed in our laboratory suggest that LRR2 and LRR4 appear to be themost crucial. The Ala-scanning data suggest that Leu103 and Ile105 in LRR4 are important forhormone binding. However, it is not clear whether these two residues make direct contact withhuman chorionic gonadotropin (hCG) or if they are necessary for the overall structural integrityof LRR4. In this work, the LHR peptide mimics of LRR4 were used for photoaffinity labeling todetermine whether Leu103 and Ile105 directly interact with hormone. Furthermore, LRR4peptides containing the photoactivable benzoylphenylalanine (Bpa) were used to determinewhether the LRR structure really exists in the LHR exodomain, whether LRR 4 interact withhCG, and which residues of LRR4 interact with hCG. Bpa was directly incorporated intodifferent positions of the LRR4 peptide sequence to examine the labeling ability of individualamino acids. The results suggest that LRR4, in particular the sequence of Lys101-Cys106,makes direct contact with hCG. However Leu103 and Ile105 do not interact with hCG but mayform the hydrophobic core of the LRR4 loop, which appears to be crucial for the LRR structure.Existing data suggest that glycoprotein hormones initially bind the exodomain. Thehormone/exodomain complex undergoes conformational adjustments and stimulates theendodomain of the receptor to generate hormone signals. The exoloops modulate hormonebinding and signaling; however, little is known about whether the hormone/exodomain complexcontacts the endodomain. To address this issue, we investigated whether the exoloops interactwith the hormone. First, we examined exoloop 3 that connects transmembrane domains 6 and 7which are important for signal generation. We present the first physical evidence that LHRexoloop 3 interacts with hCG.

No description available.

In an attempt to synthesize a photoreactive geranylcysteine derivative, A, with an appropriate photoprobe to be studied as a mimic for farnesylated protein, B, the following syntheses were carried out. The hydroxyl group of geraniol was protected with DHP/PPTs to generate 1 (98.1%). Allylic oxidation of 1 by using TBHP/SeO2 yielded 2 (31.5%). A modified oxidation increased the yield of 2 (34.4%). Treatment of 2 with BTC/pyridine afforded 3 (86.0%). Reaction of 3 with NaN3/DMF gave 8 and 9 (49.4%). Deprotection of this mixture under PPTs/EtOH afforded 10 and 11 (64.1%). Because of the unexpected reaction of 3 with N3-, we focused on alternative target molecules 12 and 13 (Figure 7). Our attempts to synthesize the first intermediates 14 and 15 in the syntheses of 12 and 13 (Scheme 14 and Scheme 15) have resulted in the isolation of the unreacted starting material.