A Survey of Universal Quantum von Neumann Architecture.

The existence of universal quantum computers has been theoretically well established. However, building up a real quantum computer system not only relies on the theory of universality, but also needs methods to satisfy requirements on other features, such as programmability, modularity, scalability, etc. To this end, here we study the recently proposed model of quantum von Neumann architecture by putting it in a practical and broader setting, namely, the hierarchical design of a computer system. We analyze the structures of quantum CPU and quantum control units and draw their connections with computational advantages. We also point out that a recent demonstration of our model would require less than 20 qubits.

N-linoleyltyrosine resisted the growth of non-small cell lung cancer cells via the regulation of CB1 and CB2 involvement of PI3K and ERK pathways.

Background: N-linoleyltyrosine (NITyr), one of the anandamide analogs, exerts activity via the endocannabinoid receptors (CB1 and CB2), which showed anti-tumor effects in various tumors. Therefore, we speculated that NITyr might show anti-non-small cell lung cancer (NSCLC) effects via the CB1 or CB2 receptor. The purpose of the investigation was to reveal the anti-tumor ability of NITyr on A549 cells and its mechanisms. Methods: The viability of A549 cells was measured by MTT assay, and the cell cycle and apoptosis were both examined by flow cytometry; in addition, cell migration was tested by wound healing assay. Apoptosis-related markers were measured by immunofluorescence. The downstream signaling pathways (PI3K, ERK, and JNK) of CB1 or CB2 were examined through Western blotting. The expressions of CB1 and CB2 were detected by immunofluorescence. Finally, the AutoDock software was used to validate the binding affinity between the targets, such as CB1 and CB2, with NITyr. Results: We found that NITyr inhibited cell viability, hindered the cell cycle, resulted in apoptosis, and inhibited migration. The CB1 inhibitor, AM251, and the CB2 inhibitor, AM630, weakened the aforementioned phenomenon. The immunofluorescence assay suggested that NITyr upregulated the expression of CB1 and CB2. Western blot analysis indicated that NITyr upregulated the expression of p-ERK, downregulated the expression of p-PI3K, and did not affect p-JNK expression. In conclusion, NITyr showed a role in inhibiting NSCLC through the activation of CB1 and CB2 receptors involved in PI3K and ERK pathways.

N-linoleyltyrosine protects neurons against Aß1-40-induced cell toxicity via autophagy involving the CB2/AMPK/mTOR/ULK1 pathway.

Beta-amyloid protein (Aß) is one of the most important pathogenic factors of Alzheimer's disease (AD). N-linoleyltyrosine (NITyr) was synthesized in our laboratory and exerted neuroprotective effects in APP/PS1 transgenic mice in previous reports. In this study, the neuroprotective effects and mechanisms of NITyr were evaluated in Aß1-40-treated primary cortical neurons for the first time in vitro. NITyr treatment attenuated cytotoxicity induced by Aß1-40, and the best effect of NITyr was observed at 1 µmol/L. NITyr treatment increased the BDNF protein expression and the ratio of p-CREB/CREB, but weakened the Caspase-3 protein expression. Meanwhile, NITyr enhanced the expressions of autophagy-related proteins (LC3-II, Beclin-1, ATG5 and ATG13). The autophagy inhibitor 3-methyladenine (3MA) reversed the effects of NITyr on cell viability and the protein expressions of neuron-related proteins, including BDNF, p-CREB and Caspase-3. The CB2 receptor antagonist AM630 weakened the neuroprotective effects of NITyr and the autophagy-related protein expression (LC3-II, Beclin-1, ATG5 and ATG13). Moreover, NITyr significantly increased the expressions of p-AMPK, p-mTOR and p-ULK1, but not p-p38. AM630 ablated the above phenomenon. Therefore, NITyr protected the neurons against Aß1-40-induced cytotoxicity by inducing autophagy, which involved the CB2/AMPK/mTOR/ULK1 pathway.

N-linoleyltyrosine exerts neuroprotective effects in APP/PS1 transgenic mice via cannabinoid receptor-mediated autophagy.

Anandamide (AEA) analogs show fair effects in counteracting the deterioration of Alzheimer's disease (AD). Our previous studies demonstrated that AEA analog-N-linoleyltyrosine (NITyr) exerted significant activities. In our current research, the role and mechanisms of NITyr were assessed in APP/PS1 mice mimicking the AD model. NITyr improved motor coordination in the rotarod test (RRT) and ameliorated spatial memory in the Morris water maze (MWM) but did not increase spontaneous locomotor activity in the open field test (OFT). In addition, NITyr protected neurons against ß-amyloid (Aß) injury via hematoxylin-eosin (HE) and Nissl staining. Moreover, the related biochemical indexes showed that NITyr reduced the levels of Aß40 and Aß42 in the hippocampus but did not affect the expression of p-APP and ß-secretase 1 (BACE1). Furthermore, the autophagy inhibitor 3-methyladenine (3 MA) attenuated the effect of NITyr on animal behaviors and neurons. Meanwhile, NITyr upregulated the expression levels of LC3-II and Beclin-1, which were weakened by AM630 (an antagonist of CB2 receptor and a weak partial agonist of CB1 receptors). AM630 also weakened the role of NITyr in animal behaviors. Thus, NITyr improved behavioral impairment and neural loss by inducing autophagy mainly mediated by the CB2 receptor, and weakly mediated by the CB1 receptor.

Circ-sirt1 inhibits growth and invasion of gastric cancer by sponging miR-132-3p/miR-212-3p and upregulating sirt1 expression.

circRNAs have been considered as a rising factor in cancers. However, the roles and mechanisms of circ-sirt1 in gastric cancer (GC) remain largely unknown. In this study, we found that the expressions of sirt1 and circ-sirt1 are decreased in tissues or serums of GC patients by real-time quantitative PCR (RT-qPCR). The expressions of miR-132-3p/miR-212-3p showed an opposite tendency in these samples. The co-transfection of miR-132-3p/miR-212-3p mimics counteracted the enhancement of sirt1 expression induced by circ-sirt1. The results of cell colony-formation assay and transwell assays demonstrated that the proliferation, migration, and invasion activities of BGC-823 cells were inhibited by circ-sirt1 overexpression or miR-132-3p/miR-212-3p knockdown, respectively. The xenograft tumor model result indicated that the circ-sirt1 overexpression suppressed the tumor growth of BGC-823 cells. The regulation of miR-132-3p/miR-212-3p between circ-sirt1 and sirt1 was verified in the mice tumor tissues. Thus, circ-sirt1 inhibited tumor growth and invasion probably by sponging miR-132-3p/miR-212-3p and upregulating sirt1 expression in GC. These findings may provide a theoretical basis for the classification of GC and a novel therapeutic target for GC patients.

Diet Quality Scores and Risk of Nasopharyngeal Carcinoma in Chinese Adults: A Case-Control Study.

Many studies show that dietary factors may affect the risk of nasopharyngeal carcinoma (NPC). We examined the association between overall diet quality and NPC risk in a Chinese population. This case-control study included 600 NPC patients and 600 matched controls between 2009 and 2011 in Guangzhou, China. Habitual dietary intake and various covariates were assessed via face-to-face interviews. Diet quality scores were calculated according to the Healthy Eating Index-2005 (HEI-2005), the alternate Healthy Eating Index (aHEI), the Diet Quality Index-International (DQI-I), and the alternate Mediterranean Diet Score (aMed). After adjustment for various lifestyle and dietary factors, greater diet quality scores on the HEI-2005, aHEI, and DQI-I-but not on the aMed-showed a significant association with a lower risk of NPC (p-trends, <0.001-0.001). The odds ratios (95% confidence interval) comparing the extreme quartiles of the three significant scores were 0.47 (0.32-0.68) (HEI-2005), 0.48 (0.33-0.70) (aHEI), and 0.43 (0.30-0.62) (DQI-I). In gender-stratified analyses, the favorable association remained significant in men but not in women. We found that adherence to the predefined dietary patterns represented by the HEI-2005, aHEI, and DQI-I scales predicted a lower risk of NPC in adults from south China, especially in men.

Diversity of sugar acceptor of glycosyltransferase 1 from Bacillus cereus and its application for glucoside synthesis.

Glycosyltransferase 1 from Bacillus cereus (BcGT1) catalyzes the transfer of a glucosyl moiety from uridine diphosphate glucose (UDP-glucose) to various acceptors; it was expressed and characterized. The specificity of acceptors was found to be broad: more than 20 compounds classified into O-, S-, and N-linkage glucosides can be prepared with BcGT1 catalysis. Based on this work, we conclude that the corresponding acceptors of these compounds must possess the following features: (1) the acceptors must contain at least one aromatic or fused-aromatic or heteroaromatic ring; (2) the reactive hydroxyl or sulfhydryl or amino group can attach either on the aromatic ring or on its aliphatic side chain; and (3) the acceptors can be a primary, secondary, or even a tertiary amine. Four representative acceptors-fluorescein methyl ester, 17-ß-estradiol, 7-mercapto-4-methylcoumarin, and 6-benzylaminopurine-were chosen as a candidate acceptor for O-, S-, and N-glucosidation, respectively. These enzymatic products were purified and the structures were confirmed with mass and NMR spectra. As all isolated glucosides are ß-anomers, BcGT1 is confirmed to be an inverting enzyme. This study not only demonstrates the substrate promiscuity of BcGT1 but also showed the great application prospect of this enzyme in bioconversion of valuable bioactive molecules.

Folate, vitamin B6, vitamin B12 and methionine intakes and risk for nasopharyngeal carcinoma in Chinese adults: a matched case-control study.

Many studies have suggested that folate-related one-carbon metabolism-related nutrients may play a role in certain cancer risks, but few studies have assessed their associations with the risk for nasopharyngeal carcinoma (NPC). In this study, we investigated the association between four folate-related one-carbon metabolism-related nutrients (folate, vitamin B6, vitamin B12 and methionine) and NPC risk in Chinese adults. A total of 600 patients newly diagnosed (within 3 months) with NPC were individually matched with 600 hospital-based controls by age, sex and household type (urban v. rural). Folate, vitamin B6, vitamin B12 and methionine intakes were measured using a validated seventy-eight-item FFQ. A higher dietary folate or vitamin B6 intake was associated with a lower NPC risk after adjusting for potential confounders. The adjusted OR of NPC for quartiles 2-4 (v. 1) were 0·66 (95% CI 0·48, 0·91), 0·52 (95% CI 0·37, 0·74) and 0·34 (95% CI 0·23, 0·50) (P(trend)<0·001) for folate and 0·72 (95% CI 0·52, 1·00), 0·55 (95% CI 0·39, 0·78) and 0·44 (95% CI 0·30, 0·63) (P(trend)<0·001) for vitamin B6. No significant association with NPC risk was observed for dietary vitamin B12 or methionine intake. The risk for NPC with dietary folate intake was more evident in the participants who were not exposed to toxic substances than in those who were exposed (P(interaction)=0·014). This study suggests that dietary folate and vitamin B6 may be protective for NPC in a high-risk population.

Study of liver cirrhosis over ten consecutive years in Southern China.

AIM: To investigate the etiology and complications of liver cirrhosis (LC) in Southern China. METHODS: In this retrospective, cross-sectional study, we identified cases of liver cirrhosis admitted between January 2001 to December 2010 and reviewed the medical records. Patient demographics, etiologies and complications were collected, and etiological changes were illustrated by consecutive years and within two time periods (2001-2005 and 2006-2010). All results were expressed as the mean ± SD or as a percentage. The χ(2) test or Student's t-test was used to analyze the differences in age, gender, and etiological distribution, and one-way analysis of variance was applied to estimate the trends in etiological changes. We analyzed the relationship between the etiologies and complications using unconditioned logistic regression, and the risk of upper gastrointestinal bleeding (UGIB) and hepatocellular carcinoma (HCC) in the major etiological groups was evaluated as ORs. A P value less than 0.05 was considered significant. Statistical computation was performed using SPSS 17.0 software. RESULTS: In this study, we identified 6719 (83.16%) male patients and 1361 (16.84%) female patients. The average age of all of the patients was 50.5 years at the time of diagnosis. The distribution of etiological agents was as follows: viral hepatitis, 80.62% [hepatitis B virus (HBV) 77.22%, hepatitis C virus (HCV) 2.80%, (HBV + HCV) 0.58%]; alcohol, 5.68%; mixed etiology, 4.95%; cryptogenic, 2.93%; and autoimmune hepatitis, 2.03%; whereas the other included etiologies accounted for less than 4% of the total. Infantile hepatitis syndrome LC patients were the youngest (2.5 years of age), followed by the metabolic LC group (27.2 years of age). Viral hepatitis, alcohol, and mixed etiology were more prevalent in the male group, whereas autoimmune diseases, cryptogenic cirrhosis, and metabolic diseases were more prevalent in the female group. When comparing the etiological distribution in 2001-2005 with that in 2006-2010, the proportion of viral hepatitis decreased from 84.7% to 78.3% (P < 0.001), and the proportion of HBV-induced LC also decreased from 81.9% to 74.6% (P < 0.001). The incidence of mixed etiology, cryptogenic cirrhosis, and autoimmune diseases increased by 3.1% (P < 0.001), 0.5% (P = 0.158), and 1.3% (P < 0.001), respectively. Alcohol-induced LC remained relatively steady over the 10-year period. The ORs of the development of UGIB between HBV and other major etiologies were as follows: HCV, 1.07; alcohol, 1.89; autoimmune, 0.90; mixed etiology, 0.83; and cryptogenic, 1.76. The ORs of the occurrence of HCC between HBV and other major etiologies were as follows: HCV, 0.54; alcohol, 0.16; autoimmune, 0.05; mixed etiology, 0.58; and cryptogenic, 0.60. CONCLUSION: The major etiology of liver cirrhosis in Southern China is viral hepatitis. However, the proportions of viral hepatitis and HBV are gradually decreasing. Alcoholic LC patients exhibit a greater risk of experiencing UGIB, and HBV LC patients may have a greater risk of HCC.

Habitual consumption of soy products and risk of nasopharyngeal carcinoma in Chinese adults: a case-control study.

BACKGROUND AND OBJECTIVES: Many studies have shown a negative association between the consumption of soy products and the risk of some cancers, but little is known about the effect of soy consumption on nasopharyngeal carcinoma. We assessed the association between the consumption of soy products on nasopharyngeal carcinoma risk in Chinese individuals. METHODS: This case-control study included 600 (448 males and 152 females) incident cases of nasopharyngeal carcinoma, and an equal number of controls, matched according to gender, age (± 3 y) and household type to the nasopharyngeal carcinoma cases. All subjects were recruited from hospitals in Guangzhou, China. A face-to-face interview was conducted with each study individual to collect general information and habitual dietary intake using a 78-item quantitative food-frequency questionnaire. Odds ratios and their 95% confidence intervals were estimated using conditional logistic regression analyses. RESULTS: The median intakes of soy foods (in protein) were 0.5/0.5, 1.4/1.7, 2.7/3.3 and 6.1/7.7 (male/female) g/d in the quartiles 1 to 4. Both univariate and multivariate analyses showed no significant association between the consumption of soy proteins or soy isoflavones and the risk of nasopharyngeal carcinoma. The adjusted odds ratios (95% confidence intervals) between extreme quartiles were 0.97 (0.66-1.45) for soy proteins and 0.97 (0.66-1.42) for total isoflavones. Null associations were also observed between intake of the individual isoflavones daidzein, genistein and glycitein and NPC risk, with adjusted odds ratios for the extreme quartiles ranging between 0.73 and 1.23. CONCLUSION: Habitual consumption of soy products had no significant effect on the risk of nasopharyngeal carcinoma in Chinese adults with a relatively low intake.

Ligand-functionalization of BPEI-coated YVO4:Bi3+,Eu3+ nanophosphors for tumor-cell-targeted imaging applications.

In this study, surface-functionalized, branched polyethylenimine (BPEI)-modified YVO4:Bi(3+),Eu(3+) nanocrystals (NCs) were successfully synthesized by a simple, rapid, solvent-free hydrothermal method. The BPEI-coated YVO4:Bi(3+),Eu(3+) NCs with high crystallinity show broad-band excitation in the λ=250 to 400 nm near-ultraviolet (NUV) region and exhibit a sharp-line emission band centered at λ=619 nm under excitation at λ=350 nm. The surface amino groups contributed by the capping agent, BPEI, not only improve the dispersibility and water/buffer stability of the BPEI-coated YVO4:Bi(3+),Eu(3+) NCs, but also provide a capability for specifically targeted biomolecule conjugation. Folic acid (FA) and epidermal growth factor (EGF) were further attached to the BPEI-coated YVO4:Bi(3+),Eu(3+) NCs and exhibited effective positioning of fluorescent NCs toward the targeted folate receptor overexpressed in HeLa cells or EGFR overexpressed in A431 cells with low cytotoxicity. These results demonstrate that the ligand-functionalized, BPEI-coated YVO4:Bi(3+),Eu(3+) NCs show great potential as a new-generation biological luminescent bioprobe for bioimaging applications. Moreover, the unique luminescence properties of BPEI-coated YVO4:Bi(3+),Eu(3+) NCs show potential to combine with a UVA photosensitizing drug to produce both detective and therapeutic effects for human skin cancer therapy.

Protein engineering of oxidosqualene-lanosterol cyclase into triterpene monocyclase.

A computational modeling/protein engineering approach was applied to probe H234, C457, T509, Y510, and W587 within Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase (ERG7), which spatially affects the C-10 cation of lanosterol formation. Substitution of Trp587 to aromatic residues supported the "aromatic hypothesis" that the π-electron-rich pocket is important for the stabilization of electron-deficient cationic intermediates. The Cys457 to Gly and Thr509 to Gly mutations disrupted the pre-existing H-bond to the protonating Asp456 and the intrinsic His234 : Tyr510 H-bond network, respectively, and generated achilleol A as the major product. An H234W/Y510W double mutation altered the ERG7 function to achilleol A synthase activity and generated achilleol A as the sole product. These results support the concept that a few-ring triterpene synthase can be derived from polycyclic cyclases by reverse evolution, and exemplify the power of computational modeling coupled with protein engineering both to study the enzyme's structure-function-mechanism relationships and to evolve new enzymatic activity.

Protein engineering of Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase into parkeol synthase.

A Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase mutant, ERG7(T384Y/Q450H/V454I), produced parkeol but not lanosterol as the sole end product. Parkeol undergoes downstream metabolism to generate compounds 9 and 10. In vitro incubation of parkeol produced a product profile similar to that of the in vivo experiment. In summary, parkeol undergoes a metabolic pathway similar to that of cycloartenol in yeast but distinct from that of lanosterol in yeast, suggesting that two different metabolic pathways of postoxidosqualene cyclization may exist in S. cerevisiae.

The cysteine 703 to isoleucine or histidine mutation of the oxidosqualene-lanosterol cyclase from Saccharomyces cerevisiae generates an iridal-type triterpenoid.

The Cys703 to Ile or His mutation within Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase ERG7 (ERG7(C703I/H)) generates an unusual truncated bicyclic rearranged intermediate, (8R,9R,10R)-polypoda-5,13E,17E,21-tetraen-3ß-ol, related to iridal-skeleton triterpenoid. Numerous oxidosqualene-cyclized truncated intermediates, including tricyclic, unrearranged tetracyclic with 17α/ß exocyclic hydrocarbon side chain, rearranged tetracyclic, and chair-chair-chair tricyclic intermediates (compounds 3-9), were also isolated from the ERG7(C703X) site-saturated mutations or the ERG7(F699T/C703I) double mutation, indicating the functional role of the Cys703 residue in stabilizing the bicyclic C-8 cation and the rearranged intermediate or interacting with Phe699, and opened a new avenue of engineering ERG7 for producing biological active agents.

Greater intake of fruit and vegetables is associated with lower risk of nasopharyngeal carcinoma in Chinese adults: a case-control study.

PURPOSE: The effect of fruit and vegetable intake on the risk of nasopharyngeal carcinoma (NPC) remains uncertain due to limited published evidence. We performed a matched case-control study to investigate the relationship between the intake of fruit and vegetables and the risk of NPC. METHODS: Between July 2009 and March 2011, 600 (448 male, 152 female), NPC incident cases from a single hospital in Guangzhou, Guangdong Province, China, a high-incidence area, were enrolled in the study. 600 controls, matched by gender, age (± 3 years) and household type (urban/rural) were also enrolled. Face-to-face interviews were used to collect habitual dietary intakes and information on various covariates. RESULTS: Multivariate conditional logistic regression analyses showed significant, dose-dependent inverse associations between the intake of vegetables, fruit or a combination of the two and the risk of NPC, even after adjustments for social-economic status, body mass index, dietary factors and other potential covariates. The adjusted odds ratios (95% confidence intervals) for NPC in the top quartile of vegetable intake, fruit intake or a combination of the two, as compared to the lowest quartile, were 0.33 (0.22-0.50), 0.70 (0.47-1.04) and 0.37 (0.25-0.55), respectively. Dark green leafy vegetables, carrots, peppers and tomatoes, citrus fruit and pome fruit showed much more pronounced benefits with regards to NPC than other types of fruit and vegetables. Interaction analyses demonstrated that the effects of total combined vegetable and fruit intake were much more significant in subjects with a higher education level (p interaction: 0.027), and the benefits of fruit were observed in males, but not in females (p interaction: 0.088). CONCLUSION: Our findings suggest that a greater consumption of fruit and vegetables may lower the risk of NPC in Chinese adults.

Mutation of isoleucine 705 of the oxidosqualene-lanosterol cyclase from Saccharomyces cerevisiae affects lanosterol's C/D-ring cyclization and 17α/ß-exocyclic side chain stereochemistry.

Site-saturated substitution in Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase at Ile705 position produced three chair-boat-chair (C-B-C) truncated tricyclic compounds, two 17α-exocyclic protosteryl intermediates, two protosteryl C-17 truncated rearranged intermediates and the normal biosynthetic product, lanosterol. These results indicated the importance of the Ile705 residue in affecting lanosterol's C/D ring stabilization including 6-6-5 tricyclic and protosteryl C-17 cations and 17α/ß-exocyclic side chain stereochemistry.

Alteration of the substrate's prefolded conformation and cyclization stereochemistry of oxidosqualene-lanosterol cyclase of Saccharomyces cerevisiae by substitution at phenylalanine 699.

The Saccharomyces cerevisiae ERG7(Phe699) mutants produced one chair-chair-chair (C-C-C) and two chair-boat-chair (C-B-C) truncated tricyclic compounds, one tetracyclic 17alpha-exocyclic unrearranged intermediate, and two 17beta-exocyclic truncated rearranged intermediates. These results provided direct evidence for the importance of the residue in affecting mechanistic transitions between C-B-C and C-C-C substrate conformation and between the 17alpha- and 17beta-exocyclic side chain stereochemistry as well as in stabilizing the 6-6-5 tricyclic and the protosteryl C-17 cations.

Importance of Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase tyrosine 707 residue for chair-boat bicyclic ring formation and deprotonation reactions.

A contact mapping strategy was applied to identify putative amino acid residues that influence the oxidosqualene-lanosterol B-ring cyclization reaction. A bicyclic intermediate with two altered deprotonation products, in conjunction with lanosterol, were isolated from the ERG7(Y707X) mutants, indicating that the Tyr707 residue may play a functional role in stabilizing the chair-boat bicyclic C-8 cation and the lanosteryl C-8/C-9 cation intermediates.

Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase: a chemistry-biology interdisciplinary study of the protein's structure-function-reaction mechanism relationships.

The oxidosqualene cyclases (EC 5.4.99-) constitute a family of enzymes that catalyze diverse cyclization/rearrangement reactions of (3S)-2,3-oxidosqualene into a distinct array of sterols and triterpenes. The relationship between the cyclization mechanism and the enzymatic structure is extremely complex and compelling. This review covers the historical achievements of biomimetic studies and current progress in structural biology, molecular genetics, and bioinformatics studies to elucidate the mechanistic and structure-function relationships of the Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase-catalyzed cyclization/rearrangement reaction.

Protein plasticity: a single amino acid substitution in the Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase generates protosta-13(17),24-dien-3beta-ol, a rearrangement product.

To provide insights into the structure-function relationships of oxidosqualene-lanosterol cyclase (ERG7) from Saccharomyces cerevisiae, the Phe699 was exchanged against hydrophilic polar uncharged residues Ser, Thr, Cys, Gln, and Tyr to characterize its product profile and functional role in ERG7 activity. Among the substitutions, only the ERG7(F699T) mutant produced novel protosta-13(17),24-dien-3beta-ol as the sole truncated rearrangement product. The results suggest that Phe699Thr mutation is likely to affect the C-17 cation stabilization during the rearrangement process.