Inhibitory effect of S-adenosylmethionine on the growth of human gastric cancer cells in vivo and in vitro

Background and Objective: S-adenosylmethionine (SAM), the most important methyl donor in human body, is generally used to treat cholestasis in clinic. In recent years, SAM has been found to have inhibitory effects on breast cancer, liver cancer and colon carcinoma. This study was to investigate the inhibitory effects of SAM on human gastric cancer cells in vivo and in vitro, and the antitumor mechanisms. Methods: The effects of SAM on the proliferation of gastric cancer SGC-7901 and MKN-45 cells were determined by MTT assay. After SGC-7901 and MKN-45 cells were treated with 0, 2, and 4 mmol/L SAM for 72 h, the expression and methylation of c-myc and urokinase type plasminogen activator (uPA) were detected by reverse transcription-polymerase chain reaction (RT-PCR) and methylation-specific PCR (MSP). Tumor xenografts were established by injecting SGC-7901 cells subcutaneously in BALB/c nude mice. The mice were randomized into low concentration group [192 μmol/(kg·day)], high concentration group [768 μmol/(kg·day)], and control group [normal saline (NS)], and received peritoneal injection of relative reagents for 15 days. The tumor size was measured, the protein and mRNA expression of c-myc and uPA were detected by immunohistochemistry and RT-PCR, and the methylation of c-myc and uPA genes was detected by MSP. Results: SAM inhibited the growth of SGC-7901 and MKN-45 cells obviously and the effects were enhanced with the increase of SAM concentration and treatment time. The mRNA expression of c-myc and uPA in SGC-7901 cells and that of uPA in MKN-45 cells significantly decreased. The c-myc and uPA genes in SGC-7901 cells and uPA gene in MKN-45 cells were partly or completely methylated after SAM treatment. The tumor volume was significantly lower in low concentration group [(618.51± 149.27) mm3] and high concentration group [(444.32 ± 118.51) mm3] than in control group [(1018.22 ± 223.07) mm3] (both P < 0.01). The inhibitory rates of tumor growth were 39.26% in low concentration group and 56.36% in high concentration group. The protein and mRNA expressions of c-myc and uPA were remarkably reduced (all P < 0.01), and the hypomethylation of c-myc and uPA genes were reversed after SAM treatment. Conclusions: SAM can inhibit the growth of human gastric cancer cells both in vivo and in vitro. The mechanism may be that SAM can reverse the hypomethylation of c-myc and uPA genes, reduce their expression, and then inhibit tumor growth.

S-adenosylmethionine in treatment of cholestasis after total parenteral nutrition: laboratory investigation and clinical application

Objective: To observe the effects of S-adenosylmethio-nine (SAMe) in the treatment of cholestasis after totalparenteral nutrition (TPN).Methods: Thirty SD rats were randomly divided intocontrol group, hypercalorie group, hypercalorie+SAMegroup, sepsis group and sepsis+SAMe group to com-pare their states of cholestasis. Sixteen patients re-ceived SAMe because of cholestasis after prolongedTPN, and the therapeutic efficacy was observed.Results: Bile flow was obviously decreased and theserum levels of total bile acid and gamma-glutamyltranspeptidase(γ-GT) were markedly increased in thehypercalorie and sepsis groups. Meanwhile, hepatocytefatty degeneration, dilatation of cholangioles, and bilesludge could be seen microscopically. SAMe adminis-tration in the hypercalorie+SAMe and sepsis+SAMegroups could increase the bile flow, decrease theserum levels of total bile acid and γ-GT, reduce thepathological damage to the liver, and clear the bilesludge in the cholangioles. Cholestasis and abnormalliver function were the main manifestations of the 16patients before SAMe administration. After SAMe treat-ment for 3 weeks, serum levels of total bilirubin, al-kaline phosphatase(AKP), γ-GT, alanine aminotrans-ferase(ALT), and aspartate aminotransferase(AST)were obviously decreased, and normalized in the 4thweek.Conclusion: SAMe could prevent and treat cholestasiswithout discontinuation of TPN.

Early treatment efficacy of S-adenosylmethionine in patients with intrahepatic cholestasis: A systematic review

BACKGROUND S-adenosylmethionine(AdoMet)is a metabolically pleiotropic molecule used to treat intrahepatic cholestasis(IHC)and chronic liver diseases.While the efficacy of AdoMet has been demonstrated previously,it has not been systematically investigated within the early weeks of treatment.AIM To systematically review the early treatment efficacy of AdoMet in adult patients with IHC.METHODS Studies reporting the efficacy of intravenous,intramuscular,or oral forms of AdoMet within 8 wk of treatment initiation were considered;three randomized and six non-randomized studies were eligible for inclusion(PROSPERO registration number CRD42018090936).Of the three randomized studies,two were double-blind and placebo-controlled,and one was comparator-controlled with unclear blinding and a relatively high risk of bias.Mean serum levels of alanine aminotransferase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP),and gamma-glutamyl transferase(γGT)following AdoMet treatment vs placebo,comparator,or baseline were summarized to determine differences in liver enzymes.Changes in patient-reported clinical symptoms of cholestasis were also summarized.RESULTS Both placebo-controlled randomized studies reported significant reductions in serum ALT levels with AdoMet vs placebo within 2 wk.One of these also reported significant ALP reductions,and the other reported significant AST andγGT reductions within 2 wk.The comparator-controlled randomized study,which had a number of notable limitations,reported significant reductions in serum ALT and AST levels with AdoMet vs potassium magnesium aspartate within 4 wk,but not within2 wk.All of the non-randomized studies(4/4)that investigated ALT,AST,ALP and/orγGT reported significant reductions in at least two of these parameters within 2 wk.Of the five studies that evaluated fatigue,reductions were observed within 2 wk in one randomized and two nonrandomized studies.The remaining two non-randomized studies reported improvements in fatigue within 6 and 8 wk.Of the four studies reporting symptoms of depression,two non-randomized studies observed improvements within 2 wk and the other two observed improvements within 17 d and 8 wk.CONCLUSION Data from both randomized and non-randomized studies suggest that AdoMet improves some biochemical liver parameters and symptoms of cholestasis within 2 wk,with further improvements observed in some studies after 4 and 8 wk of treatment.

EFFECT OF UP-REGULATION OF S-ADOMET SYNTHETASE ON TAXOL-INDUCED APOPTOSIS IN HUMAN BREAST CANCER CELLS

Objective: To investigate the gene regulation of taxolinduced apoptosis Methods: Northern blot hybridization, enzyme activity assay of S AdoMet synthetase and flow cytometry were performed in the investigation of expression in the mRNA level and biological action of S AdoMet synthetase in taxol induced apoptosis in human breast cancer cell line (BCap 37) Results: Up regulation of S AdoMet synthetase expression was resulted by taxol treatment and the expression peaked at 48 hours Moreover,the up regulation of S AdoMet synthetase was associated with cytotoxicity of anti microtubule agents including taxol and colchicine Inhibition rate of S AdoMet synthetase activity by 1% DMSO was 34% in taxol treated cells and 14% in taxol untreated cells compared to control groups, respectively Posttreatment with 1% DMSO following pretreatment with individual antitumor agent for 3 hrs promoted apoptotic cell death of taxol ,colchicine ,and adriamycin treated Bcap37 cells Conclusion : The induction of apoptosis enhanced by post treatment with DMSO in taxol treated cells is probably linked to its inhibition on enzyme activity of S AdoMet synthetase ,suggesting that the increased expression of S AdoMet synthetase possibly plays an important role in protecting cells from DNA fragmentation in taxol induced apoptosis Accepted July 26, 1998 This work was supported by the National High Biotechnology Foundation of China and a grant from the Natural Science Foundation of Zhejiang Province, China

A Prospective, Open-Label, 12 Week Trial of S-adenosylmethionine in the Symptomatic Treatment of Alzheimer’s Disease

Objective: To determine if treatment with S-adenosylmethionine (SAM-e) might lead to cognitive and behavioral improvement in patients with Alzheimer’s disease (AD). Interventions: We conducted a prospective, open-label study of six subjects who were given oral SAM-e over 12 weeks and measured the effects on cognition and behavior. Outcome measures: Outcome measures of cognition and behavior included the Alzheimer’s Disease Assessment Scale-Cognitive subscale (ADAS-Cog), Mini-Mental State Examination (MMSE), Behave-AD, Clinical Global Impression Scale (CGI), Hamilton Rating Scale for Depression (HAM-D), informant version, Blessed Dementia Scale to assess activities of daily living (ADL), the Physical Self-Maintainance Scale (PSMS), and the Lawton-Brody IADL Scale to measure instrumental activities of daily living. Results: At study completion, two subjects were “moderately improved” and 4 were “minimally improved” on the CGI. Five subjects improved on the ADAS-Cog by an average of 20%. No significant side effects were reported. Conclusions: In this small open label study, SAM-e appeared to have a beneficial effect in patients with AD, but the small subject number didn’t provide enough power to show statistical significance. Controlled trials with adequate statistical power to investigate its utility in AD are warranted.

抑制GhSAMS基因表达降低陆地棉对棉铃虫的抗性

【目的】探究陆地棉S-腺苷甲硫氨酸合成酶(S-adenosylmethionine synthetase,SAMS)基因在棉花对棉铃虫抗性响应中的功能。【方法】利用实时荧光定量聚合酶链式反应(real-time quantitative polymerase chain reaction,qRT-PCR)分析GhSAMS基因在棉铃虫取食下的表达模式。利用病毒诱导的基因沉默(virus-induced gene silencing,VIGS)技术抑制GhSAMS基因的表达,通过分析棉铃虫的生长发育(体重和体长的变化量)、取食偏好性以及棉花叶片受害等级等,初步探究GhSAMS基因的抗虫功能。【结果】qRT-PCR结果表明,棉花叶片中的GhSAMS基因在棉铃虫取食后表达量增加。利用VIGS技术获得了pTRV2::GhSAMS沉默棉株。与饲喂野生型棉花叶片的棉铃虫相比,饲喂pTRV2::GhSAMS棉花叶片的棉铃虫生长发育更快;棉铃虫对pTRV2::GhSAMS棉花叶片表现出更强的取食偏好;二氨基联苯胺(3,3’-diaminobenzidine,DAB)染色结果分析表明,与野生型棉花相比,沉默GhSAMS基因的棉花叶片细胞中H_(2)O_(2)的累积量增多。【结论】抑制GhSAMS基因表达降低了陆地棉对棉铃虫的抗性,GhSAMS可作为提高棉花对棉铃虫抗性的候选基因。

不同来源S-腺苷甲硫氨酸合酶在大肠杆菌中的表达及催化应用

S-腺苷甲硫氨酸(S-adenosylmethionine,SAM)是一种重要的代谢中间体,对机体代谢活动的正常运行起重要作用,它是由底物L-甲硫氨酸和ATP在SAM合酶催化下生成的,目前主要应用于医药行业。该研究首先以蜡状芽孢杆菌Bacillus cereus和谷氨酸棒杆菌Corynebacterium glutamicum基因组为模板扩增出SAM合酶编码基因BcmetK和CgmetK,以pETDueT1质粒为载体,以大肠杆菌E.coli BL21(DE3)为底盘细胞,构建了SAM合成菌株E.coli BL21/pETDuet1-BcmetK和E.coli BL21/pETDuet1-CgmetK。其次,针对SAM合成菌株全细胞催化合成体系条件进行了优化,重组大肠杆菌E.coli BL21/pETDuet1-BcmetK在最优条件[L-甲硫氨酸浓度50 mmol/L、ATP浓度50 mmol/L、1.2%(体积分数)的OD_(600)值约9.0的细胞悬浮液、600 mmol/L pTSoNa、50 mmol/L MgSO_(4)、100 mmol/L K_(2)SO_(4)、45℃、pH 8.0]下,连续转化5 h,获得了464 mg/L的SAM。重组大肠杆菌E.coli BL21/pETDuet1-CgmetK在最优条件[L-甲硫氨酸浓度50 mmol/L、ATP浓度40 mmol/L、0.8%(体积分数)的OD_(600)值约9.0的细胞悬浮液、800 mmol/L pTSoNa、50 mmol/L MgSO 4、100 mmol/L K_(2)SO 4、45℃、pH 8.5]下,连续转化5 h,获得了528 mg/L的SAM,可见,谷氨酸棒杆菌来源的SAM合酶催化能力优于蜡状芽孢杆菌来源的,更有利于SAM的合成。该研究成功构建了SAM合成菌株,虽然产量水平不高,但为SAM的可持续生物合成提供了重要借鉴。

野生大豆S-腺苷甲硫氨酸合成酶基因的克隆及功能分析

干旱、盐碱和低温等非生物逆境是危害作物诸多因素中最为严重的自然灾害,它可以使作物减产,甚至死亡。目前通过生物技术手段获得可利用的抗性基因是提高植物抗性的重要途径。东北野生大豆具有丰富的基因资源,是基因克隆的理想材料。从低温(4℃)、干旱(30%PEG)及盐胁迫(200mmolL-1NaCl)处理的东北野生大豆幼苗叶片中提取总RNA,经反转录合成cDNA第一链,并以此链为模板,从已构建的盐胁迫全长cDNA文库和东北野生大豆盐胁迫EST数据库中筛选出与渗透胁迫直接相关的EST序列,根据该序列设计一对PCR引物扩增S-腺苷甲硫氨酸(SAM)合成酶基因的全长序列,经Blast比较分析,确定所获得的SAMS基因全长序列。构建以pBI121为基础的CaMV35S启动子调控的植物表达载体;利用农杆菌介导法将其导入烟草,获得了180株转基因烟草,并进行了低温、干旱和盐胁迫处理,通过测定在不同胁迫处理下的生理指标,分析了基因的功能。野生大豆的SAMS基因在烟草中的超量表达提高了转基因烟草的抗低温、干旱和耐盐能力。

荔枝败育胚S-腺苷甲硫氨酸合成酶基因的全长扩增和序列分析

从荔枝‘桂味’的败育胚中提取总RNA,利用GeneRacerTMKit将RNA经去磷酸化反应、去mRNA的帽子结构及RNA Oligo连接,反转录合成cDNA,以cDNA为模板,分别用SSH分离得到的胚败育相关差异表达S-腺苷甲硫氨酸合成酶基因的部分cDNA序列(599 bp)设计出3’和5’端基因特异引物,进行PCR末端扩增。荔枝败育胚的S-腺苷甲硫氨酸合成酶基因序列全长为1515 bp,编码393个氨基酸,与其它物种的S-腺苷甲硫氨酸合成酶基因的核苷酸序列同源性在79％-82％之间,氨基酸序列同源性在88％-91％之间。结果表明所获得的基因为与荔枝胚败育相关的S-腺苷甲硫氨酸合成酶基因。

甘蔗S-腺苷甲硫氨酸合成酶基因(ScSAM)的克隆及表达

利用RT-PCR和RACE技术从甘蔗品种新台糖22(ROC 22)中克隆获得SAM基因的cDNA序列,命名为ScSAM,GenBank登录号为KC172558。用生物信息学方法预测分析其序列,cDNA全长1466 bp,含有1个1191 bp的完整开放阅读框(ORF),编码396个氨基酸,与高粱和玉米等植物的SAM蛋白有很高的相似性。系统进化树分析显示,甘蔗ScSAM与高粱的SAM蛋白亲缘关系较近。Real-time PCR分析表明ScSAM为组成型表达,在根中的表达量最高,是叶中表达量的3.6倍。其在黑穗病菌胁迫和低温(4℃)、聚乙二醇(PEG)、NaCl非生物胁迫下均被诱导表达,但表达模式不同;在H2O2胁迫下其表达被抑制。推测其可能参与甘蔗抗黑穗病过程,且在甘蔗抗寒、抗旱、抗盐和抗氧化等胁迫过程中也起某种作用。

糜子SAMS基因的克隆及其在干旱复水中的表达模式分析

以糜子抗旱节水研究中获得的一个与S-腺苷甲硫氨酸合成酶（SAMS）基因同源性较高的EST序列为基础,采用RT-PCR技术从糜子中分离到一个SAMS基因的全长cDNA序列（命名为PmSAMS）,全长1293bp,编码396个氨基酸,具有SAMS典型的N端结构域、中间结构域及C端结构域。糜子、马铃薯、拟南芥、甜菜、大麦、荔枝、番茄和水稻8种植物SAMS的氨基酸序列多重比较分析表明,不同植物的SAMS的氨基酸相似程度非常高（92%~97%）,其中糜子与水稻的相似性最高（97%）,说明SAMS基因在植物进化中非常保守。PmSAMS基因在糜子幼苗干旱及复水过程中的半定量RT-PCR表达模式分析表明,在干旱早期（土壤含水量36%）诱导该基因大量表达,而干旱程度更严重时（土壤含水量为24%）其表达受到严重抑制,表达量比对照还低;严重干旱后复水2h,其表达量增强至干旱早期的表达量,而复水6h后表达量降低至对照（干旱处理前）水平。可见,PmSAMS基因的表达涉及糜子响应干旱胁迫及干旱后复水过程,可能是糜子抗旱节水的关键基因。该基因的克隆为进一步探讨其应用于农作物抗旱节水性的遗传改良奠定了基础。

S-腺苷甲硫氨酸代谢途径相关基因在小麦水分胁迫中的表达

以小麦品种‘晋麦47’为材料,利用半定量RT-PCR方法,对S-腺苷甲硫氨酸代谢途径中的S-腺苷甲硫氨酸合成酶（SAMS）基因、S-腺苷甲硫氨酸脱羧酶（SAMDC）基因和γ-谷氨酰半胱氨酸合成酶（-γECS）基因在正常供水、PEG-6000模拟水分胁迫和复水过程中小麦叶片的表达模式进行了分析。结果表明,3个基因在正常生长情况下有一定量的表达,SAMS和SAMDC基因在水分胁迫早期（PEG-6000胁迫6、12、244、8 h）上调表达,水分胁迫后期（PEG-6000胁迫75 h）表达量下降;复水后3~6 h上调表达,复水9 h后表达量下调至对照水平。-γECS基因在水分胁迫阶段呈上调表达,复水后表达量下调至对照水平。可见,小麦SAMS、SAMDC和-γECS基因的表达都受水分胁迫诱导,同时,SAMS与SAMDC基因还参与水分胁迫后的复水调节,说明S-腺苷甲硫氨酸代谢途径在小麦抗旱节水中具有重要作用。

大肠杆菌S-腺苷甲硫氨酸合成酶基因的克隆与表达

应用PCR技术从E.coli JM 109中扩增出长约1.1kb的S-腺苷甲硫氨酸合成酶基因，将其插入高表达载体pET11c的NdeI和BamHI位点中，转化E.coli BL 21 (DE3)。SDS-PAGE和薄层扫描结果表明，重组菌S-腺苷甲硫氨酸合成酶的表达量占菌体总可溶性蛋白含量的58.3%。酶活测定结果表明，重组菌S-腺苷甲硫氨酸合成酶的活力比宿主菌高7倍。

高盐下条斑紫菜光合特性和S-腺苷甲硫氨酸合成酶基因表达的变化

为了研究条斑紫菜耐盐机理,对条斑紫菜叶状体进行了高盐胁迫处理,继而采用氧电极法测量了光合放氧速率和呼吸耗氧速率的变化,采用实时荧光定量PCR技术测量了S-腺苷甲硫氨酸合成酶(命名为PySAMS)基因的表达变化。结果显示藻体的光合与呼吸作用均受到高盐度海水的显著影响,随着盐度的增加,光合放氧率逐渐降低,呼吸耗氧率也逐渐降低。高盐度海水对PySAMS基因表达量也产生了显著影响,40和50盐度的海水诱导了PySAMS表达,但60至80盐度的海水却不同程度地抑制了PySAMS表达。据此推测,在面对较高盐度胁迫时条斑紫菜叶状体将逐步降低体内新陈代谢以度过不良环境。

海藻酸钠明胶协同固定S-腺苷甲硫氨酸合成酶

以海藻酸钠和明胶为载体,对S-腺苷甲硫氨酸合成酶进行固定化。再用戊二醛对其进一步交联,增强固定化酶的稳定性。考察了海藻酸钠和明胶质量分数、CaCl2质量分数、酶和载体比例以及交联剂戊二醛体积分数等因素对固定化酶的影响。结果表明,最佳固定化条件为:海藻酸钠质量分数2.0%、明胶质量分数1.0%、CaCl2质量分数4.0%、固定化酶量为2.5 g/L凝胶、戊二醛体积分数0.6%。交联固定化酶热稳定性得到大幅度提高,在50℃下保温5 h仍保留72%的活力,而游离酶则完全失活。交联固定化酶在碱性溶液中的稳定性较高,在pH=8.0～9.0的缓冲液中4℃保温10 h酶活性仍保留87%以上。将交联固定化酶用于S-腺苷甲硫氨酸的合成,连续反应8批次后酶活性仍保留65%。

茶树S-腺苷甲硫氨酸合成酶基因的克隆和序列分析

从茶树叶片中提取总RNA ,经反转录合成cDNA第一链。以cDNA第一链为模板 ,分别用三对PCR引物扩增SAM合成酶基因的中间主片段、 3 端和 5 端片段 ,最后经BLAST比较及重叠区域拼接得到完整的SAM基因序列。所得序列长 130 3bp ,编码 394个氨基酸。与中华猕猴桃、番茄、长春花SAM合成酶基因的核苷酸序列的同源性分别为 87% ,83 %和 83%。氨基酸序列与三角杨、猕猴桃、番茄、长春花等的SAM氨基酸序列的同源性为 92 %～ 90 %。证实所获得的基因序列为茶树SAM合成酶基因。该基因的克隆为今后进一步开展茶树逆境生理。

S-腺苷甲硫氨酸合成酶反应条件的优化

优化了重组毕赤酵母表达的S-腺苷甲硫氨酸合成酶催化L-甲硫氨酸(Met)和ATP合成S-腺苷甲硫氨酸的条件,确定了该酶的最适酶活力检测条件为20mmol/L的L-Met,26mmol/L的ATP,52mmol/L的MgCl2,300mmol/L的KCl,8mmol/L的还原型谷胱甘肽,100mmol/L的Tris,反应液pH 8.5,35°C反应1h,比活力达到23.84U/mg。该酶还可以催化以DL-Met代替L-Met为底物的S-腺苷甲硫氨酸合成反应,以降低生产成本。

壳聚糖固定化S-腺苷甲硫氨酸合成酶

在大肠杆菌中重组表达了S-腺苷甲硫氨酸合成酶,然后以壳聚糖为载体,戊二醛为交联剂,对酶进行固定化研究.结果表明,最佳固定化条件为：壳聚糖质量浓度为2.5g/dL、戊二醛体积分数为0.8％、固定化酶量为6 mg/mL、固定化时间为12 h,该条件下所得固定化酶活性回收率为76％,固定化酶热稳定性较好,在55℃下保温5h仍保留53％的活力,而游离酶在50℃下保温5h则完全失活.固定化酶在碱性溶液环境的稳定性较高,在pH 7.5～9.0的缓冲液中4℃保温10 h酶活性仍保留80％以上.将固定化酶用于S-腺苷甲硫氨酸的合成,连续反应5批次后,酶活性仍保留64％.在底物三磷酸腺苷（ATP）浓度为30 mmol/L的条件下,固定化酶催化底物ATP的转化率超过95％.

甘薯S-腺苷甲硫氨酸合成酶基因克隆与表达

从实验室建立的甘薯冷胁迫抑制消减文库中分离出一cDNA片段,经NCBI比对后发现该片段与其它植物的S-腺苷甲硫氨酸合成酶基因具有90%的同源性,根据相关物种S-腺苷甲硫氨酸合成酶基因cDNA序列设计引物,以甘薯总RNA为模板,经RT-PCR扩增首次获得全长1182bp的甘薯SAMS完全编码区,NCBI比对分析结果表明:该片段与不同种属植物sams基因的编码区序列的核苷酸相似性达85.48%,所推导的氨基酸序列相似性达93.6%。根据核苷酸序列和氨基酸序列分别构建了SAMS系统进化树,从分子水平阐明了植物种属间的亲缘进化关系,为其种质资源利用提供理论依据。利用该序列与原核表达载体pET32a连接构建融合表达载体pET-SAMS,酶切鉴定后转入大肠杆菌BL21,在不同温度下诱导3h后均表达出一63KDa大小融合蛋白。

番茄S-腺苷蛋氨酸脱羧酶基因SlSAMDC1的克隆与序列分析

以蔓陀罗S-腺苷蛋氨酸脱羧酶全长cDNA序列为信息探针,筛选NCBI番茄EST数据库,依据同源EST信息,经人工拼接、RT-PCR及RACE技术验证,获得了1个新的SAMDC基因家族成员,命名为SlSAMDC1(GenBank登录号:EF550528),并利用染色体步移技术克隆了879bp的上游调控区域。SlSAMDC1cDNA序列全长1847bp,5′-UTR和3′-UTR分别长523和241bp;存在3个ORF(微型uORF、小型uORF和主ORF),主ORF编码360个氨基酸的SAMDC酶原;SlSAMDC1基因组序列全长3648bp,有3个内含子,均位于5′-UTR,所有内含子的剪切位点均符合真核生物"GT-AG"规则。SlSAMDC1基因与其它植物来源SAMDC基因同源性较高,与人、大肠杆菌以及酵母的同源性较低。表达谱分析发现,SlSAM-DC1基因在番茄根、茎、叶、花蕾、果实等器官中均表达,果实中的表达量相对较高。生物信息学分析表明,SlSMDC1基因的上游调控序列存在多个顺式作用元件,如W-box、TATA-box、CAAT-box等。