In vitro inhibition potency of malononitrile derivatives on the activity of two pentose phosphate pathway enzymes: accompanied by molecular docking evaluation.

Many disorders, including cancer and malaria, could be targeted via the pentose phosphate pathway (PPP), whose products are key in biosynthetic reactions in cells. The goal of this study was to find new PPP inhibitors. The inhibition effects of malononitrile derivatives on Glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) were analyzed through in vitro experiments. Besides, molecular docking studies were performed to predict the interactions having role in inhibition of compounds. K i constants of derivatives were found between 4.24 ± 0.46-69.63 ± 7.75 µM for G6PD and 1.91 ± 0.12-95.07 ± 11.08 µM for 6PGD. Derivatives indicated non-competitive inhibition on both enzymes except for compound 4. The findings of the molecular docking studies revealed that free-binding energy estimations agreed with in vitro data. The structure of these malononitrile derivatives may guide for drug discovery in targeting the PPP.

Affinity gel synthesis from the p-aminobenzoic acid derivative 4-amino-2-methylbenzoic acid and purification of polyphenol oxidase from various plant sources.

The polyphenol oxidase (PPO) enzyme, which causes enzymatic browning, has been repeatedly purified from fruit and vegetables by affinity chromatography. In the present research, Sepharose 4B-l-tyrosine-4-amino-2-methylbenzoic acid, a novel affinity gel for the purification of the PPO enzyme with high efficiency, was synthesized. Additionally, Sepharose 4B-l-tyrosine-p-aminobenzoic acid affinity gel, known in the literature, was also synthesized, and 9.02, 16.57, and 28.13 purification folds were obtained for the PPO enzymes of potato, mushroom, and eggplant by the reference gel. The PPO enzymes of potato, mushroom, and eggplant were purified 41.17, 64.47, and 56.78-fold from the new 4-amino-2-methylbenzoic acid gel. Following their isolation from the new affinity column, the assessment of PPO enzyme purity involved the utilization of SDS-PAGE. According to the results from SDS-PAGE and native PAGE, the molecular weight of each enzyme was 50 kDa. Then, the inhibition effects of naringin, morin hydrate, esculin hydrate, homovanillic acid, vanillic acid, phloridzin dihydrate, and p-coumaric acid phenolic compounds on purified potato, mushroom, and eggplant PPO enzyme were investigated. Among the tested phenolic compounds, morin hydrate was determined to be the most potent inhibitor on the potato (Ki: 0.07 ± 0.03 µM), mushroom (Ki: 0.7 ± 0.3 µM), and eggplant (Ki: 4.8 ± 1.2 µM) PPO enzymes. The studies found that the weakest inhibitor was homovanillic acid for the potato (Ki: 1112 ± 324 µM), mushroom (Ki: 567 ± 81 µM), and eggplant (Ki: 2016.7 ± 805.6 µM) PPO enzymes. Kinetic assays indicated that morin hydrate was a remarkable inhibitor on PPO.

Structure-Activity Relationship of Methyl 4-Aminobenzoate Derivatives as Being Drug Candidate Targeting Glutathione Related Enzymes: in Vitro and in Silico Approaches.

A thiol compound, glutathione, is essential for healthy cell defence against xenobiotics and oxidative stress. Glutathione reductase (GR) and glutathione S-transferase (GST) are two glutathione-related enzymes that function in the antioxidant and the detoxification systems. In this study, potential inhibitory effects of methyl 4-aminobenzoate derivatives on GR and GST were examined in vitro. GR and GST were isolated from human erythrocytes with 7.63 EU/mg protein and 5.66 EU/mg protein specific activity, respectively. It was found that compound 1 (methyl 4-amino-3-bromo-5-fluorobenzoate with Ki value of 0.325±0.012 µM) and compound 5 (methyl 4-amino-2-nitrobenzoate with Ki value of 92.41±22.26 µM) inhibited GR and GST stronger than other derivatives. Furthermore, a computer-aided method was used to predict the binding affinities of derivatives, ADME characteristics, and toxicities. Derivatives 4 (methyl 4-amino-2-bromobenzoate) and 6 (methyl 4-amino-2-chlorobenzoate) were estimated to have the lowest binding energies into GR and GST receptors, respectively according to results of in silico studies.

Molecular Docking Studies and the Effect of Fluorophenylthiourea Derivatives on Glutathione-Dependent Enzymes.

Cancer is a serious problem affecting the health of all human societies. Chemotherapy refers to the use of drugs to kill cancer or the origin of cancer. In the past three decades, researchers have studied about proteins and their roles in the production of cancer cells. Glutathione S-transferases (GSTs) are a superfamily of enzymes that play a key role in cellular detoxification, protecting against reactive electrophiles attacks, including chemotherapeutic agents. Glutathione reductase (GR) is an important antioxidant enzyme involved in protecting the cell against oxidative stress. In this current study, GST and GR enzymes were purified from human erythrocytes using affinity chromatography. GR was obtained with a specific activity of 5.95 EU/mg protein and a 52.38 % yield. GST was obtained with a specific activity of 4.88 EU/mg protein and a 74.88 % yield. The effect of fluorophenylthiourea derivatives on the purified enzymes was investigated. Afterward, KI values were found to range from 23.04±4.37 µM-59.97±13.45 µM for GR and 7.22±1.64 µM-41.24±2.55 µM for GST. 1-(2,6-difluorophenyl)thiourea was showed the best inhibition effect for both GST and GR enzymes. The relationships of inhibitors with 3D structures of GST and GR were explained by molecular docking studies.

Screening of in vitro and in silico effect of Fluorophenylthiourea compounds on glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase enzymes.

Inhibition studies of enzymes in the pentose phosphate pathway (PPP) have recently emerged as a promising technique for pharmacological intervention in several illnesses. Glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) are the most important enzymes of the PPP. For this purpose, in the current study, we examined the effect of some fluorophenylthiourea on G6PD and 6PGD enzyme activity. These compounds exhibited moderate inhibitory activity against G6PD and 6PGD with KI values ranging from 21.60 ± 8.42 to 39.70 ± 11.26 µM, and 15.82 ± 1.54 to 29.97 ± 5.72 µM, respectively. 2,6-difluorophenylthiourea displayed the most potent inhibitory effect for G6PD, and 2-fluorophenylthiourea demonstrated the most substantial inhibitory effect for 6PGD. Furthermore, the molecular docking analyses of the fluorophenylthioureas, competitive inhibitors, were performed to understand the binding interactions at the enzymes' binding site.

Cytotoxic effect, enzyme inhibition, and in silico studies of some novel N-substituted sulfonyl amides incorporating 1,3,4-oxadiazol structural motif.

The acetylcholinesterase and carbonic anhydrase inhibitors (AChEIs and hCAIs) remain key therapeutic agents for many bioactivities such as anti-Alzheimer and antiobesity antiepileptic, anticancer, antiinfective, antiglaucoma, and diuretic effects. Here, it has been attempted to discover novel multi-target AChEIs and hCAIs that are highly potent, orally bioavailable, may be brain penetrant, and have higher effectiveness at lower doses than tacrine and acetazolamide. After detailed investigations both in vitro and in silico, novel N-substituted sulfonyl amide derivatives (6a-j) were determined to be highly potent inhibitors for AChE and hCAs (KIs are in the range of 23.11-52.49 nM, 18.66-59.62 nM, and 9.33-120.80 nM for AChE, hCA I, and hCA II, respectively). Moreover, according to the cytotoxic effect studies, such as the ADME-Tox, cortex neuron cells, and neuroblastoma SH-SY5Y cell line, compounds 6a, 6d, and 6h, which are the most potent representative versus the target enzymes, were identified as orally bioavailable, highly selective, and brain preferentially distributed AChEIs and hCAIs. The docking studies revealed precise binding modes between 6a, 6d, and 6h and hCA II, hCA I, and AChE, respectively. The results presented here might provide a solid basis for further investigation into more potent AChEIs and hCAIs.

In vitro and in silico interactions of antiulcer, glucocorticoids and urological drugs on human carbonic anhydrase I and II isozymes.

Carbonic anhydrases (CAs, Enzyme Commission 4.2.1.1) convert carbon dioxide to bicarbonate in metabolism and use Zn2+ ions as a cofactor for their catalytic activity. The activators or inhibitors of CA-I and CA-II, which are the most abundant CA isozymes in erythrocytes, have pharmacological applications in medicine. So, investigation of drug-protein interaction of these isozymes is significant. On this basis, the objective of this study was to clarify the primer effects of widely used drugs on the activity of human CA-I and CA-II enzymes and elucidate the inhibition mechanism through molecular docking studies. For this aim isozymes were purified from human erythrocytes by affinity chromatography technique. Then inhibition profiles of antiulcer, glucocorticoids, and urological drugs were investigated. As a result, while budesonide had the highest inhibitory potency on hydratase activity of hCA-I with the IC50 of 0.08 mM, levofloxacin showed the highest inhibition effect on hCA-II with the IC50 of 0.886 mM. The most effective inhibitor on the esterase activity of isozymes was found as fluticasone propionate with the Ki values of 0.0365 ± 0.016 mM and 0.054 ± 0.018 mM respectively. However, by molecular docking study, it was estimated that budesonide showed maximum inhibition potency for both isozymes with the free binding energy of -7.58 and -6.97 kcal/mol, respectively. Consequently, it was observed that some of the drugs studied did not show any inhibitory effect. Drug-enzyme interactions were also estimated by molecular docking. This study could contribute to the discovery of new drug candidates and as well as target proteins.

Methyl benzoate derivatives as inhibitors of pentose phosphate pathway, which promotes cancer progression and drug resistance: An in silico study supported by in vitro results.

The pentose phosphate pathway (PPP), whose products are vital in biosynthetic events, is targeted in the treatment of many diseases such as cancer and malaria. The objective of this study was to identify new PPP inhibitors. The inhibition effects of methyl 4-amino benzoates on glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) were analyzed through in vitro experiments and molecular docking studies were used to estimate inhibition mechanisms. IC50 values of compounds were found between 100.8 and 430.8 µM for G6PD and 206 and 693.2 µM for 6PGD. Molecular docking analysis showed that compound 1 was found the most effective inhibitor against hG6PD and compound 4 had the highest inhibitory potency against h6PGD with the estimated binding energy of -6.71 and -7.61 kcal/mol, respectively. In conclusion, it was determined that in vitro and in silico outcomes of the study were highly correlated with each other. The structure of these benzoates may aid in the development of drugs that target the PPP.

A study on the effects of inhibition mechanism of curcumin, quercetin, and resveratrol on human glutathione reductase through in vitro and in silico approaches.

Glutathione reductase (GR) is a major antioxidant enzyme essential to maintain GSH/GSSG ratio by catalyzing recovery of reduced glutathione (GSH) from oxidized glutathione (GSSG). Because of this vital task, the inhibition of GR is an important target in the treatment of many diseases, so we aimed to identify natural and new GR inhibitors to be guide for drug design.For this purpose, two different approaches were used. The first one is in vitro inhibition, the first phase of which was the purification of the enzyme from human erythrocyte by 2', 5'-ADP Sepharose 4B affinity chromatography, and then the in vitro inhibition effects of curcumin, quercetin, and resveratrol were examined. The second one is in silico study, which was performed to elucidate the drug-likeness, active site identification and inhibition mechanisms of these compounds.hGR was isolated from human erythrocytes with 7.036 EU/mg protein specific activity and 48.97% yield. Then, IC50 values were as 17.25 ± 3.8 µM, 57.8 ± 14.2 µM, and 520 ± 96.7 µM for curcumin, quercetin, and resveratrol respectively. Docking studies of compounds were performed against hGR receptors with induced-fit docking method. The compound showed Glide score as 10.519 kcal/mol, -9.789, and -8.133 respectively.In conclusion, it was seen that curcumin is the much better inhibitor than quercetin and resveratrol for hGR according to both in vitro and in silico studies. Curcumin, a potential inhibitor of hGR, can be used in drug design to target the glutathione system in cellular injury.Communicated by Ramaswamy H. Sarma.

Effects of different LED light spectra on rainbow trout (Oncorhynchus mykiss): in vivo evaluation of the antioxidant status.

Rainbow trout (Oncorhynchus mykiss) farming is one of the major aquacultures in Turkey. Some conditions in fish farming can induce oxidative stress leading to the deterioration in properties such as appearance/color, texture, and flavor in fish meat. This situation may cause the consumer not to prefer edible fish. Although there are some studies on the impacts of light intensity on fish welfare, the changes in the antioxidant enzyme activities have not been elucidated. In the current study, it was intended to examine in rainbow trout how cultivating under different wavelengths affects the antioxidant enzymes and acetylcholine esterase (AChE) activity, because its activity is associated with oxidative stress, and also the determination of which light is suitable for fish welfare was aimed. Rainbow trout larvae were grown under four lights with different wavelengths: natural sunlight and incandescent long-wave (red light), medium-wave (green light), and short-wave (blue light) LED light. The experiment lasted for 64 days. Biochemical assays were carried on in the brain, gill, and liver of rainbow trout. Antioxidant enzymes and AChE activity, which play an important role in the central nervous system, were assayed. In gill tissues, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glucose 6 phosphate dehydrogenase (G6PD), glutathione reductase (GR), glutathione S-transferase (GST), and AChE activities increased under all three light wavelengths. In the liver, while activities of antioxidant enzymes and AChE decreased in red light, all of them increased in blue and green light. In the brain, GPx, GST, G6PD, and SOD activities were reduced but AChE activity did not alter under all three light sources. In conclusion, light sources with different spectral structures caused important changes in the activities of antioxidant enzymes in rainbow trout. On this basis, it may be thought that this may be a response to the changing redox status of a cell. Based on our results, blue light sources may be suggested for fish welfare in rainbow trout culture, and providing fish welfare by changing light sources can be easy and cheap in fish farming.

Purification of Polyphenol Oxidase from Potato and Investigation of the Inhibitory Effects of Phenolic Acids on Enzyme Activity.

BACKGROUND: Polyphenol Oxidase (PPO) belongs to the oxidoreductase enzyme family. METHODS: Here, PPO was purified from potato using Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity chromatography. It determined the interactions between some phenolic acids and the enzyme. RESULTS: The enzyme was obtained with a specific activity of 15333.33 EU/mg protein and 7.87- fold purification. It was found that phenolic acids exhibited inhibitory properties for PPO. The IC50 values of the phenolic acids were found in the range of 0.36-2.12 mM, and their Ki values were found in the range of 0.28± 0.07-1.72±0.32 mM. It was determined that all studied compounds displayed a competitive inhibition effect. Among these compounds, 3-hydroxybenzoic acid was found to be the most effective PPO inhibitor (Ki: 0.28±0.07 mM). CONCLUSION: Investigating the inhibition kinetics of the enzyme will simplify the testing of PPO inhibitor candidates.

Inhibition effects of some antidepressant drugs on pentose phosphate pathway enzymes.

The glucose metabolism in the pentose cycle is essential to the source of NADPH. Deficiency of these enzymes have been linked to depression and psychotic disorders. Depression is an increasingly prevalent mental disorder which may cause loss of labor. Antidepressant drugs are commonly employed in treatments of mood disorders and anxiety treatment. The purpose of this study is to investigate the effects of aripiprazole, mirtazapine, risperidone, escitalopram and haloperidol on the activity of 6-phosphogluconate dehydrogenase (6PGD) and glucose-6-phosphate dehydrogenase (G6PD) enzymes purified from human erythrocytes. It was found that aripiprazole, mirtazapine, risperidone, escitalopram and haloperidol show effective inhibitor properties on purified G6PD and 6PGD enzymes. The IC50 values of these drugs were found in the range of 26.34 µM-5.78 mM for 6PGD and 16.26 µM-3.85 mM for G6PD. The Ki values of the drugs were found in the range of 30.21 ± 4.31 µM-4.51 ± 1.83 mM for 6PGD and 14.12 ± 3.48 µM-4.98 ± 1.14 mM for G6PD. Usage of drugs with significant biological effects may be a hazard in some conditions.

Inhibition effects of quinones on aldose reductase: Antidiabetic properties.

Diabetes mellitus is a chronic metabolic disease characterized by abnormal glucose metabolism. Aldose reductase (AR) is the first enzyme in the polyol pathway and converts glucose to sorbitol. It plays a vital role as a glucose reducing agent and is involved in the pathophysiology of diabetic complications. In this study, we purified AR from sheep kidney with a specific activity of 2.00 EU/mg protein and 133.33- fold purification After the purification of the AR enzyme, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed and the molecular weight of the enzyme was found approximately as 38 kDa. The inhibition effects of eight quinones were studied against AR. The quinones were potent inhibitors of AR with Ki values in the range of 0.07-20.04 µM. Anthraquinone showed the best potential inhibitory effects against AR. All compounds exhibited noncompetitive inhibition against AR. These compounds may be selective inhibitors of this enzyme. AR inhibition is an essential strategy for the attenuation and prevention of diabetic complications.

The behavior of some chalcones on acetylcholinesterase and carbonic anhydrase activity.

Carbonic anhydrase (CA) has a key role in respiration, carbon dioxide and bicarbonate transport. Acetylcholinesterase (AChE) is a serine hydrolase and mostly abundant at neuromuscular junctions and cholinergic brain synapses. Inhibitors of these enzymes could aid in illuminating the role in disease processes. In this study, we separately purified CA I and CA II from human erythrocytes. The purity of the enzymes was showed by SDS-PAGE analysis. We also investigated the inhibition of seven chalcones toward hCA I, hCA II, and AChE. The chalcones were effective inhibitors of the cytosolic CA isoforms (hCA I and hCA II) and AChE with Ki values in the range of 1.83-7.05 µM for hCA I, 0.59-5.50 µM for hCA II, and 0.61-86.11 µM for AChE. All compounds were showed competitive inhibition aganist both enzymes. These compounds can be a potent inhibitor of AChE enzyme and both cytosolic CA isoenzymes which are commonly used in the pharmaceutical and medical industries.

Antidiabetic and antiparasitic potentials: Inhibition effects of some natural antioxidant compounds on α-glycosidase, α-amylase and human glutathione S-transferase enzymes.

The glutathione S-transferase (GST) was purified from fresh blood erythrocytes using affinity column chromatography. Also, α-amylase from porcine pancreas and α-glycosidase from Saccharomyces cerevisiae were used as target enzymes. In this study, these compounds were tested on α-amylase, α-glycosidase, and GST enzymes and demonstrated effective inhibitor compounds with Ki values in the range of 8.34-40.78 µM against GST, and 120.53-892.36 nM against α-glycosidase. Additionally, the phenolic molecules were tested for the inhibition of α-amylase enzyme which determined effective inhibition profile with IC50 values in the range of 175.01-626.58 nM. Indeed, these molecules can be elective inhibitors of GST, α-glycosidase and α-amylase enzymes as antidiabetic and antiparasitic agents.

Inhibition effects of pesticides on glutathione-S-transferase enzyme activity of Van Lake fish liver.

Glutathione-S-transferases (GSTs) have a function in xenobiotic metabolism. They are a significant multifunctional family with a wide variety of catalytic activities. In the current study, we determined in vitro inhibition effects of 2,4-dichlorophenoxyacetic acid dimethylamine salt (2,4-D DMA), haloxyfop-P-methyl, glyphosate isopropylamine, dichlorvos, and λ-cyhalothrin on purified GST. For this purpose, GST were purified from Van Lake fish (Chalcalburnus tarichii Pallas) liver with 29.25 EU mg-1 specific activity and 10.76% yield using GSH-agarose affinity chromatographic method. The pesticides were tested at various concentrations on in vitro GST activity. Ki constants were calculated as 0.17 ± 0.01, 0.25 ± 0.05, 3.72 ± 0.32, 0.42 ± 0.06, and 0.025 ± 0.004 mM, for 2,4-D DMA, haloxyfop-P-methyl, glyphosate isopropylamine, dichlorvos, and λ-cyhalothrin, respectively. λ-Cyhalothrin showed a better inhibitory effect compared to the other pesticides. The inhibition mechanisms of λ-cyhalothrin were competitive, while the other pesticides were noncompetitive.

Inhibitory properties of some heavy metals on carbonic anhydrase I and II isozymes activities purified from Van Lake fish (Chalcalburnus Tarichi) gill.

In this study, CA I and II isoenzymes were purified from Van Lake fish gills by using Sepharose-4B-L-tyrosine-sulfanilamide affinity chromatography and to determine the effects of some metals on the enzyme activities. For purified CA I isoenzyme, yield, specific activity, and purification fold were obtained as 42.07%, 4948.12 EU/mg protein, and 116.61 and for CA II isoenzyme, 7%, 1798.56 EU/mg protein, and 42.38 respectively. Activity of CA was determined by measuring "CO2-hydratase activity". Purity control was checked by SDS-PAGE. In vitro inhibitory effect of Cu2+, Ag+, Cd2+, Ni2+ metal ions, and arsenic (V) oxide were also examined for both isozymes activities. Whereas Cu2+, Ag+, Cd2+, and Ni2+ ions showed inhibitory effects on both isozymes, arsenic (V) oxide showed activation effect. IC50 values were calculated by drawing activity %-[I] graphs for metal ions exhibiting inhibitory effects. IC50 values were determined as 3.39, 6.38, 13.52, and 206 µM for CA I isozyme and 6.16, 20.29, 46, and 223 µM for CA II isozyme respectively.

Evaluation of chalcones as inhibitors of glutathione S-transferase.

Glutathione S-transferases (GSTs) are the superfamily of multifunctional detoxification isoenzymes and play an important role in cellular signaling. In the present study, potential inhibition effects of chalcones were tested against human GST. For this purpose, GST was purified from human erythrocytes with 5.381 EU⋅mg-1 specific activity and 51.95% yield using a GSH-agarose affinity chromatographic method. The effects of chalcones on in vitro GST activity were tested at various concentrations. Ki constants of chalcones were found in the range of 7.76-41.93 µM. According to the results, 4-fluorochalcone showed a better inhibitory effect compared with the other compounds. The inhibition mechanisms of 2'-hydroxy-4-methoxychalcone and 4-methoxychalcone were noncompetitive, whereas the inhibition mechanisms of 4'- hydroxychalcone, 4- fluorochalcone, and 4,4'- diflurochalcone were competitive.

Discovery of potent carbonic anhydrase, acetylcholinesterase, and butyrylcholinesterase enzymes inhibitors: The new amides and thiazolidine-4-ones synthesized on an acetophenone base.

Compounds containing nitrogen and sulfur atoms can be widely used in various fields, including industry, medicine, biotechnology, and chemical technology. Among them, amides of acids and heterocyclic compounds have an important place. These amides and thiazolidine-4-ones showed good inhibitory action against butyrylcholinesterase (BChE), acetylcholinesterase (AChE), and human carbonic anhydrase isoforms. AChE exists at high concentrations in the brain and red blood cells. BChE is an important enzyme that is plentiful in the liver, and it is released into the blood in a soluble form. They were demonstrated to have effective inhibition profiles with Ki values of 23.76-102.75 nM against hCA I, 58.92-136.64 nM against hCA II, 1.40-12.86 nM against AChE, and 9.82-52.77 nM against BChE. On the other hand, acetazolamide showed Ki value of 482.63 ± 56.20 nM against hCA I, and 1019.60 ± 163.70 nM against hCA II. Additionally, Tacrine inhibited AChE and BChE, showing Ki values of 397.03 ± 31.66 and 210.21 ± 15.98 nM, respectively.

A compendium of expression patterns of cholesterol biosynthetic enzymes in the mouse embryo.

Cholesterol and its biosynthetic pathway intermediates and derivatives are required for many developmental processes including membrane biogenesis, transmembrane receptor signaling, steroid biogenesis, nuclear receptor activation, and posttranslational modification of hedgehog (Hh) proteins. To perform such multifaceted tasks depends on stringent regulation of expression of cholesterol biosynthetic enzymes (CBEs). We established for a whole organism, for the first time, the 3D expression pattern of all genes required for cholesterol biosynthesis (CBS), starting from acetyl-CoA and ending with cholesterol. This data was produced by high-throughput in situ hybridization on serial sections through the mouse fetus. The textually annotated image data were seamlessly integrated into the METscout and GenePaint public databases. This novel information helps in the understanding of why CBEs are expressed at particular locations within the fetus. For example, strong CBE expression is detected at sites of cell proliferation and also where cell growth increases membrane surface, such as in neurons sprouting axons and forming synapses. The CBE data also sheds light on the spatial relationship of cells and tissue that express sonic Hh (Shh) and produce cholesterol, respectively. We discovered that not all cells expressing Shh are capable of CBS. This finding suggests novel ways by which cholesterylation of Shh is regulated.