压力超负荷下bcl—2、bax蛋白对兔左室细胞凋亡的影响

目的：探讨超负荷时兔左室心肌细胞bcl-2和bax蛋白表达对兔左室心肌细胞凋亡的影响。方法：采取末端脱核苷酸转移酶介导的dUTP－生物素平移末端标记（TUNEL）技术和链酶亲和素－生物素－过氧化物酶复合物（SABC）免疫组化方法，观察持续压力超负荷下免左室心肌凋亡的动态变化及bcl-2和bax蛋白的表达。结果：对照组出现极少量凋亡细胞，表达少量bcl-2蛋白，不表达bax蛋白。术后凋亡阳性心肌细胞数和bcl-2蛋白阳性表达心肌细胞数迅速增加，两者在心衰组最高，凋亡阳性心肌细胞数在术后第3天多于术后第7天。左室心肌细胞仅在术后第1组和心衰组表达bax蛋白。结论：在持续压力负荷所致心力衰竭的全过程，bcl-2蛋白都以与了抑制心肌细胞凋亡的调节，bax蛋白可能只以与了心肌细胞凋亡的启动。     

大肠腺瘤中细胞凋亡和增殖相关基因的表达与意义

目的：探讨大肠腺瘤中细胞凋亡和增殖相关基因的表达与意义。方法：用脱氧核糖核酸末端转移酶介导的TUNEL法缺口末端标记和免疫组化技术，检测45例大肠腺瘤组织细胞的原位凋亡（AI）、原位增殖（KI）及bcl-2、bax基因表达；并设立20例正常大肠粘膜和40例大肠癌为对照组，探讨细胞凋亡和细胞增殖在大肠癌早期发生中的作用。结果：正常结肠粘膜有少量的bcl-2、bax和ki－67（用KI表示）表达及少量凋亡细胞存在，但无异常表达。大肠腺瘤中bcl-2表达和KI明显增加，与正常组相比P均＜0.05；AI和bax表达轻度增加，与正常相比P＜0.05。bax与AI表达呈正相关（P＜0.01），bcl－2和bax及AI呈负相关。大肠癌中bcl-2表达和KI表达虽增加，但与腺瘤相比无统计学差异P＞0.05；大肠癌组织中AI和bax表达明显增加且与腺瘤组相比P＜0.05。结论：大肠癌发生早期即腺瘤中就有细胞凋亡调控基因及增殖基因的表达异常，且以抗凋亡基因bcl-2和增殖基因表达占主导地位。该基因的表达异常可能是大肠癌发生的一个较早期分子标志；细胞凋亡增加和bax表达异常可能是大肠癌发生的一个相对较早期分子生物学事件。早期检测抗细胞凋亡基因和增殖基因，有助于对大肠癌早期发生的评估。     

毒胡萝卜素诱导K562细胞凋亡及其调控机制的研究

目的探讨毒胡萝卜索（TG）对K562细胞凋亡诱导作用及其调控机制。方法Hoechst33258染色荧光显微镜观察凋亡细胞形态改变；Annexin V—FITC／PI双染检测细胞凋亡率变化；RT—PCR检测bcl-2、bax、bcl—XL 、XIAP、survivin基因表达变化并通过免疫组织化学技术检测其在蛋白质水平的表达。结果TG作用后，K562细胞呈典型的凋亡细胞形态；细胞凋亡率均明显升高（P〈0.05），且在一定范围内呈浓度和时间依赖性；bax、bcl—XL、XIAP mRNA和蛋白质表达上调，survivin mRNA和蛋白质表达下调，bcl-2／bax比率降低。结论TG可诱导K562细胞发生内质网应激反应性凋亡，其机制可能与Bax表达上调、survivin表达下调有关，bcl-XL XIAP表达上调可能发挥拮抗凋亡的作用。     

辐射对前列腺增生组织中bcl-2和bax表达的影响及临床意义

目的 探讨前列腺增生组织中bcl—2和bax的表达以及β射线内照射对bcl—2和bax表达的影响。方法 应用免疫组织化学法检测9例正常前列腺(NP)、15例良性前列腺增生(BPH)及35例实施^90Sr／^90Yβ射线照射后前列腺增生组织中bcl—2和bax的表达。结果 NP和BPH上皮组织bcl—2阳性表达均高于间质(P＜0．01)；BPH组织上皮和间质中bcl-2表达阳性串高于NP(P＜0．01)；NP上皮细胞中bax表达高于BPH(P＜O．05)；BPH上皮和问质细胞中bcl—2表达高于bax(P＜0．01)；NP上皮和问质中bcl—2与bax表达无显著差异(P＞0．05)。与对照组相比，应用^90Sr／^90Yβ射线内照射4、7、15d后BPH上皮和间质中bcl—2明显下降，bax阳性细胞率明显升高(P＜0．01)。结论 bcl-2和bax与前列腺细胞凋亡的调节有关，β射线能使前列腺组织中bcl—2和bax含量发生变化，促使前列腺细胞凋亡。     

当归红芪超滤膜提取物抑制过氧化氢诱导的大鼠心肌细胞凋亡及相关基因表达

目的 探讨当归红芪超滤膜提取物对心肌细胞凋亡相关基因bcl-2、bax蛋白表达的影响.方法 用高浓度的过氧化氢(400 μmol/L)在Wistar乳鼠原代培养的心肌细胞上建立细胞凋亡模型,用不同浓度的当归红芪超滤物(3.75、7.5、15 g/L)进行治疗.光镜下观察细胞形态;逆转录-多聚酶链反应和蛋白印迹法检测bcl-2、bax蛋白在心肌细胞中的表达情况.结果 与正常对照组相比,高浓度过氧化氢损伤组bcl-2 mRNA及蛋白表达显著降低(P<0.05);bax mRNA及蛋白表达显著增加(P<0.05);bcl-2/bax比值显著降低(P<0.01),差异具有统计学意义.与损伤组比较,高浓度和中浓度药物治疗组bcl-2 mRNA及其蛋白表达显著增加(P<0.05);bax mRNA及其蛋白表达显著降低(P<0.05);bcl-2/bax比值显著增加(P<0.01),差异具有统计学意义.低浓度药物治疗组则对bcl-2、bax表达无显著改变.结论 当归红芪超滤膜提取物可通过上调bcl-2/bax的比值抑制心肌细胞的凋亡,对心肌细胞具有抗凋亡的保护作用.     

bax/bcl-2蛋白比值及凋亡细胞在妊娠期高血压疾病胎盘组织中的表达趋势研究

目的探讨妊娠期高血压疾病产妇胎盘组织中bax/bcl-2蛋白比值及凋亡细胞表达趋势。方法采用免疫组化SP法对6例正常产妇和18例妊娠期高血压疾病产妇的胎盘组织bax/bcl-2蛋白比值检测、TUNEL法检测凋亡细胞。结果妊娠期高血压组、子痫前期轻度、重度组bax/bcl-2蛋白比值及凋亡细胞表达数值呈增高趋势,且均高于正常组,具有显著性差异（P〈0.01）。结论 bax/bcl-2蛋白表达比值在妊娠期高血压疾病的发生和发展中失衡,胎盘细胞凋亡可能起着重要作用。     

促红细胞生成素预处理在心肌缺氧复氧损伤中对凋亡相关基因表达影响的研究

目的：观察促红细胞生成素（erythropoietin,EPO）预处理在大鼠心肌缺氧复氧损伤（hypoxia/reoxygenation,H/R）中的抗凋亡效应以及对凋亡相关基因bcl-2及bax表达的影响。方法：Wistar成年雄性大鼠60只,分为2组,分别为对照组,EPO预处理组（EPO组）,每组30只,EPO组大鼠经腹腔注射5000U/kg重组人促红细胞生成素（Recombinant human erythropoietin,RHuEPO）,对照组注射同体积生理盐水。2组各15只大鼠于给药24h后,检测各项指标,其余15只大鼠置于常压缺氧环境中（O27%）12h后,移至常压常氧环境中2h,予H/R损伤,之后采取心肌标本,DNA末端转移酶标记法（TUNEL法）检测心肌细胞凋亡,免疫组化检测凋亡效应酶胱天蛋白酶-3（caspase-3）、凋亡相关基因B细胞淋巴瘤/白血病-2（B-cell lymphoma/leukemia-2,bcl-2）及B细胞淋巴瘤/白血病相关x蛋白（Bcl-associated x protein,bax）蛋白表达水平,计算bcl-2/bax比值。结果：H/R损伤前2组心肌细胞凋亡率,caspase-3以及bax蛋白表达水平无显著性差异（P〉0.05）,EPO组bcl-2蛋白表达水平、bcl-2/bax比值显著高于对照组（P〈0.01）。H/R损伤后2组心肌细胞凋亡率,caspase-3、bax及bcl-2蛋白表达水平显著高于损伤前（P〈0.01）,而bcl-2/bax比值显著低于损伤前（P〈0.01）,EPO组的心肌细胞凋亡率、caspase-3蛋白表达水平显著低于对照组（P〈0.05,P〈0.01）,而bcl-2蛋白表达水平以及bcl-2/bax比值显著高于对照组（P〈0.05,P〈0.01）,2组bax蛋白表达水平差异无显著性（P〉0.05）。结论：EPO预处理在心肌H/R损伤中具有显著的抗凋亡效应;这一效应与其上调抗凋亡基因bcl-2的表达有关。     

促红细胞生成素预处理在心肌缺氧复氧损伤中对凋亡相关基因表达影响的研究

目的:观察促红细胞生成素(erythropoietin,EPO)预处理在大鼠心肌缺氧复氧损伤(hypoxia/reoxygenation,H/R)中的抗凋亡效应以及对凋亡相关基因bcl-2及bax表达的影响。方法:Wistar成年雄性大鼠60只,分为2组,分别为对照组,EPO预处理组(EPO组),每组30只,EPO组大鼠经腹腔注射5000U/kg重组人促红细胞生成素(Recombinant human erythropoietin,RHuEPO),对照组注射同体积生理盐水。2组各15只大鼠于给药24h后,检测各项指标,其余15只大鼠置于常压缺氧环境中(O27%)12h后,移至常压常氧环境中2h,予H/R损伤,之后采取心肌标本,DNA末端转移酶标记法(TUNEL法)检测心肌细胞凋亡,免疫组化检测凋亡效应酶胱天蛋白酶-3(caspase-3)、凋亡相关基因B细胞淋巴瘤/白血病-2(B-cell lymphoma/leukemia-2,bcl-2)及B细胞淋巴瘤/白血病相关x蛋白(Bcl-associated x protein,bax)蛋白表达水平,计算bcl-2/bax比值。结果:H/R损伤前2组心肌细胞凋亡率,caspase-3以及bax蛋白表达水平无显著性差异(P>0.05),EPO组bcl-2蛋白表达水平、bcl-2/bax比值显著高于对照组(P<0.01)。H/R损伤后2组心肌细胞凋亡率,caspase-3、bax及bcl-2蛋白表达水平显著高于损伤前(P<0.01),而bcl-2/bax比值显著低于损伤前(P<0.01),EPO组的心肌细胞凋亡率、caspase-3蛋白表达水平显著低于对照组(P<0.05,P<0.01),而bcl-2蛋白表达水平以及bcl-2/bax比值显著高于对照组(P<0.05,P<0.01),2组bax蛋白表达水平差异无显著性(P>0.05)。结论:EPO预处理在心肌H/R损伤中具有显著的抗凋亡效应;这一效应与其上调抗凋亡基因bcl-2的表达有关。     

人参强心滴丸治疗大鼠心力衰竭的作用机制研究

目的研究人参强心滴丸治疗大鼠充血性心力衰竭（CHF）的作用机制。方法采用腹主动脉缩窄法复制CHF大鼠模型，分假手术组，模型组，人参强心滴丸高剂量组、低剂量组和对照组。采用流式细胞技术观察人参强心滴丸对CHF大鼠心肌细胞凋亡及相关调控基因bax和bcl-2蛋白表达的影响。结果模型组大鼠心肌细胞凋亡率明显升高，bax蛋白表达增强，bcl-2蛋白表达减弱；各用药组心肌细胞凋亡率明显下降，bax蛋白表达减弱，bcl-2蛋白表达增强。结论人参强心滴丸可调整bax和bcl-2的蛋白表达强度，降低心肌细胞凋亡率，逆转心室重塑，改善CHF预后。     

bax、bcl-2和caspase-3基因在肝星状细胞株HSC-T6中的表达

目的：研究灌服赤芍水提物后的犬药物血清作用于肝星状细胞株HSC-T6基因蛋白表达的变化。方法：采用乙醛造模后的肝星状细胞株HSC-T6细胞作为酒精性肝纤维化的体外研究模型；以赤芍水提物给彼格犬一次性灌胃．取给药后2小时的血清作为实验药物血清。以免疫细胞化学法检测药物血清对HSC—T6作用72小时后bax、bcl-2、caspase-33种基因蛋白表达情况，并与乙醛造模后的HSC—T6细胞相比较。结果：乙醛造模后的HSC-T5细胞中bcl-2的表达较正常培养组细胞增加，bax、caspase-3表达降低；药物血清作用后的HSC-T6细胞中bcl-2的表达较造模组的HSC-T6细胞显著降低，bax、caspase-3的表达较模型组细胞显著增加。结论：赤芍水提物入血后可能是通过bax、bcl-2、casoase-3等基因异常表达来实现对HSC-T6的抑制增殖及促进凋亡作用。     

A thermodynamic definition of protein domains

Protein domains are conspicuous structural units in globular proteins, and their identification has been a topic of intense biochemical interest dating back to the earliest crystal structures. Numerous disparate domain identification algorithms have been proposed, all involving some combination of visual intuition and/or structure-based decomposition. Instead, we present a rigorous, thermodynamically-based approach that redefines domains as cooperative chain segments. In greater detail, most small proteins fold with high cooperativity, meaning that the equilibrium population is dominated by completely folded and completely unfolded molecules, with a negligible subpopulation of partially folded intermediates. Here, we redefine structural domains in thermodynamic terms as cooperative folding units, based on m-values, which measure the cooperativity of a protein or its substructures. In our analysis, a domain is equated to a contiguous segment of the folded protein whose m-value is largely unaffected when that segment is excised from its parent structure. Defined in this way, a domain is a self-contained cooperative unit; i.e., its cooperativity depends primarily upon intrasegment interactions, not intersegment interactions. Implementing this concept computationally, the domains in a large representative set of proteins were identified; all exhibit consistency with experimental findings. Specifically, our domain divisions correspond to the experimentally determined equilibrium folding intermediates in a set of nine proteins. The approach was also proofed against a representative set of 71 additional proteins, again with confirmatory results. Our reframed interpretation of a protein domain transforms an indeterminate structural phenomenon into a quantifiable molecular property grounded in solution thermodynamics.     

In vivo protein stabilization based on fragment complementation and a split GFP system

Protein stabilization was achieved through in vivo screening based on the thermodynamic linkage between protein folding and fragment complementation. The split GFP system was found suitable to derive protein variants with enhanced stability due to the correlation between effects of mutations on the stability of the intact chain and the effects of the same mutations on the affinity between fragments of the chain. PGB1 mutants with higher affinity between fragments 1 to 40 and 41 to 56 were obtained by in vivo screening of a library of the 1 to 40 fragments against wild-type 41 to 56 fragments. Colonies were ranked based on the intensity of green fluorescence emerging from assembly and folding of the fused GFP fragments. The DNA from the brightest fluorescent colonies was sequenced, and intact mutant PGB1s corresponding to the top three sequences were expressed, purified, and analyzed for stability toward thermal denaturation. The protein sequence derived from the top fluorescent colony was found to yield a 12 °C increase in the thermal denaturation midpoint and a free energy of stabilization of -8.7 kJ/mol at 25 °C. The stability rank order of the three mutant proteins follows the fluorescence rank order in the split GFP system. The variants are stabilized through increased hydrophobic effect, which raises the free energy of the unfolded more than the folded state; as well as substitutions, which lower the free energy of the folded more than the unfolded state; optimized van der Waals interactions; helix stabilization; improved hydrogen bonding network; and reduced electrostatic repulsion in the folded state.     

Experimental support for the evolution of symmetric protein architecture from a simple peptide motif

The majority of protein architectures exhibit elements of structural symmetry, and "gene duplication and fusion" is the evolutionary mechanism generally hypothesized to be responsible for their emergence from simple peptide motifs. Despite the central importance of the gene duplication and fusion hypothesis, experimental support for a plausible evolutionary pathway for a specific protein architecture has yet to be effectively demonstrated. To address this question, a unique "top-down symmetric deconstruction" strategy was utilized to successfully identify a simple peptide motif capable of recapitulating, via gene duplication and fusion processes, a symmetric protein architecture (the threefold symmetric β-trefoil fold). The folding properties of intermediary forms in this deconstruction agree precisely with a previously proposed "conserved architecture" model for symmetric protein evolution. Furthermore, a route through foldable sequence-space between the simple peptide motif and extant protein fold is demonstrated. These results provide compelling experimental support for a plausible evolutionary pathway of symmetric protein architecture via gene duplication and fusion processes.     

Fibrillation precursor of superoxide dismutase 1 revealed by gradual tuning of the protein-folding equilibrium

Although superoxide dismutase 1 (SOD1) stands out as a relatively soluble protein in vitro, it can be made to fibrillate by mechanical agitation. The mechanism of this fibrillation process is yet poorly understood, but attains considerable interest due to SOD1’s involvement in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). In this study, we map out the apoSOD1 fibrillation process from how it competes with the global folding events at increasing concentrations of urea: We determine how the fibrillation lag time (τ_lag) and maximum growth rate (ν_max) depend on gradual titration of the folding equilibrium, from the native to the unfolded state. The results show that the agitation-induced fibrillation of apoSOD1 uses globally unfolded precursors and relies on fragmentation-assisted growth. Mutational screening and fibrillation m-values (∂ log τ_lag/∂[urea] and ∂ log ν_max/∂[urea]) indicate moreover that the fibrillation pathway proceeds via a diffusely bound transient complex that responds to the global physiochemical properties of the SOD1 sequence. Fibrillation of apoSOD1, as it bifurcates from the denatured ensemble, seems thus mechanistically analogous to that of disordered peptides, save the competing folding transition to the native state. Finally, we examine by comparison with in vivo data to what extent this mode of fibrillation, originating from selective amplification of mechanically brittle aggregates by sample agitation, captures the mechanism of pathological SOD1 aggregation in ALS.     

Membrane protein thermodynamic stability may serve as the energy sink for sorting in the periplasm

Thermodynamic stabilities are pivotal for understanding structure–function relationships of proteins, and yet such determinations are rare for membrane proteins. Moreover, the few measurements that are available have been conducted under very different experimental conditions, which compromises a straightforward extraction of physical principles underlying stability differences. Here, we have overcome this obstacle and provided structure–stability comparisons for multiple membrane proteins. This was enabled by measurements of the free energies of folding and the m values for the transmembrane proteins PhoP/PhoQ-activated gene product (PagP) and outer membrane protein W (OmpW) from Escherichia coli. Our data were collected in the same lipid bilayer and buffer system we previously used to determine those parameters for E. coli outer membrane phospholipase A (OmpLA). Biophysically, our results suggest that the stabilities of these proteins are strongly correlated to the water-to-bilayer transfer free energy of the lipid-facing residues in their transmembrane regions. We further discovered that the sensitivities of these membrane proteins to chemical denaturation, as judged by their m values, was consistent with that previously observed for water-soluble proteins having comparable differences in solvent exposure between their folded and unfolded states. From a biological perspective, our findings suggest that the folding free energies for these membrane proteins may be the thermodynamic sink that establishes an energy gradient across the periplasm, thus driving their sorting by chaperones to the outer membranes in living bacteria. Binding free energies of these outer membrane proteins with periplasmic chaperones support this energy sink hypothesis.     

Folding without charges

Surface charges of proteins have in several cases been found to function as “structural gatekeepers,” which avoid unwanted interactions by negative design, for example, in the control of protein aggregation and binding. The question is then if side-chain charges, due to their desolvation penalties, play a corresponding role in protein folding by avoiding competing, misfolded traps? To find out, we removed all 32 side-chain charges from the 101-residue protein S6 from Thermus thermophilus. The results show that the charge-depleted S6 variant not only retains its native structure and cooperative folding transition, but folds also faster than the wild-type protein. In addition, charge removal unleashes pronounced aggregation on longer timescales. S6 provides thus an example where the bias toward native contacts of a naturally evolved protein sequence is independent of charges, and point at a fundamental difference in the codes for folding and intermolecular interaction: specificity in folding is governed primarily by hydrophobic packing and hydrogen bonding, whereas solubility and binding relies critically on the interplay of side-chain charges.     

Functional modulation of a protein folding landscape via side-chain distortion

Ultrahigh-resolution (< 1.0 Å) structures have revealed unprecedented and unexpected details of molecular geometry, such as the deformation of aromatic rings from planarity. However, the functional utility of such energetically costly strain is unknown. The 0.83 Å structure of α-lytic protease (αLP) indicated that residues surrounding a conserved Phe side-chain dictate a rotamer which results in a ∼6° distortion along the side-chain, estimated to cost 4 kcal/mol. By contrast, in the closely related protease Streptomyces griseus Protease B (SGPB), the equivalent Phe adopts a different rotamer and is undistorted. Here, we report that the αLP Phe side-chain distortion is both functional and conserved in proteases with large pro regions. Sequence analysis of the αLP serine protease family reveals a bifurcation separating those sequences expected to induce distortion and those that would not, which correlates with the extent of kinetic stability. Structural and folding kinetics analyses of family members suggest that distortion of this side-chain plays a role in increasing kinetic stability within the αLP family members that use a large Pro region. Additionally, structural and kinetic folding studies of mutants demonstrate that strain alters the folding free energy landscape by destabilizing the transition state (TS) relative to the native state (N). Although side-chain distortion comes at a cost of foldability, it suppresses the rate of unfolding, thereby enhancing kinetic stability and increasing protein longevity under harsh extracellular conditions. This ability of a structural distortion to enhance function is unlikely to be unique to αLP family members and may be relevant in other proteins exhibiting side-chain distortions.     

Retro-translocation of mitochondrial intermembrane space proteins

The content of mitochondrial proteome is maintained through two highly dynamic processes, the influx of newly synthesized proteins from the cytosol and the protein degradation. Mitochondrial proteins are targeted to the intermembrane space by the mitochondrial intermembrane space assembly pathway that couples their import and oxidative folding. The folding trap was proposed to be a driving mechanism for the mitochondrial accumulation of these proteins. Whether the reverse movement of unfolded proteins to the cytosol occurs across the intact outer membrane is unknown. We found that reduced, conformationally destabilized proteins are released from mitochondria in a size-limited manner. We identified the general import pore protein Tom40 as an escape gate. We propose that the mitochondrial proteome is not only regulated by the import and degradation of proteins but also by their retro-translocation to the external cytosolic location. Thus, protein release is a mechanism that contributes to the mitochondrial proteome surveillance.Mitochondrial biogenesis is essential for eukaryotic cells. Because most mitochondrial proteins originate in the cytosol, mitochondria had to develop a protein import system. Given the complex architecture of these organelles, with two membranes and two aqueous compartments, protein import and sorting require the cooperation of several pathways. The main entry gate for precursor proteins is the translocase of the outer mitochondrial membrane (TOM) complex. Upon entering mitochondria, proteins are routed to different sorting machineries (1–5).Reaching the final location is one step in the maturation of mitochondrial proteins that must be accompanied by their proper folding. The mitochondrial intermembrane space assembly (MIA) pathway for intermembrane space (IMS) proteins illustrates the importance of coupling these processes because this pathway links protein import with oxidative folding (6–10). Upon protein synthesis in the cytosol, the cysteine residues of IMS proteins remain in a reduced state, owing to the reducing properties of the cytosolic environment (11, 12). After entering the TOM channel, precursor proteins are specifically recognized by Mia40 protein, and their cysteine residues are oxidized through the cooperative action of Mia40 and Erv1 proteins (7, 13–17). Mia40 is a receptor, folding catalyst, and disulfide carrier, and the Erv1 protein serves as a sulfhydryl oxidase. The oxidative folding is believed to provide a trapping mechanism that prevents the escape of proteins from the IMS back to the cytosol (10, 13, 18). Our initial result raised a possibility that the reverse process can also occur, as we observed the relocation of in vitro imported Tim8 from mitochondria to the incubation buffer (13). Thus, we sought to establish whether and how this process can proceed in the presence of the intact outer membrane (OM). Our study provides, to our knowledge, the first characterization of the mitochondrial protein retro-translocation. The protein retro-translocation serves as a regulatory and quality control mechanism for the mitochondrial IMS proteome.     

Pancreatic stone protein – sepsis and the riddles of the exocrine pancreas

Pancreatic stone protein (PSP), discovered in the 1970ies, was first associated with stone formation during chronic pancreatitis. Later, the same protein was independently detected in islet preparations and named regenerating protein 1 (REG1). Additional isoforms of PSP, including pancreatitis-associated protein (PAP), belong to the same protein family. Although the names indicate a potential function in stone formation or islet regeneration, involvements in cellular processes were only suggestive and never unequivocally proven. We established an association between PSP levels in patient blood samples and the development of sepsis. In this review, written in connection with receiving the Lifetime Achievement Award of the European Pancreatic Club, the evolution of the sepsis aspect of PSP is described. We conclude that the true functional properties of this fascinating pancreatic protein still remain an enigma.     

Computing protein stabilities from their chain lengths

New amino acid sequences of proteins are being learned at a rapid rate, thanks to modern genomics. The native structures and functions of those proteins can often be inferred using bioinformatics methods. We show here that it is also possible to infer the stabilities and thermal folding properties of proteins, given only simple genomics information: the chain length and the numbers of charged side chains. In particular, our model predicts ΔH(T), ΔS(T), ΔC_p, and ΔF(T) —the folding enthalpy, entropy, heat capacity, and free energy—as functions of temperature T; the denaturant m values in guanidine and urea; the pH-temperature-salt phase diagrams, and the energy of confinement F(s) of the protein inside a cavity of radius s. All combinations of these phase equilibria can also then be computed from that information. As one illustration, we compute the pH and salt conditions that would denature a protein inside a small confined cavity. Because the model is analytical, it is computationally efficient enough that it could be used to automatically annotate whole proteomes with protein stability information.