枯草杆菌α-淀粉酶在一些色谱体系中的热力学和超热力学研究

通过测定不同温度范围的热力学平衡常数、焓变、熵变、自由能变和补偿温度,研究了枯草杆菌α-淀粉酶在几种色谱介质上的热力学和超热力学。结果表明,在RP-C18反相介质、Zn2+螯合的Sepharose fast-flow亲和介质和WCX-1阳离子交换介质上,当温度分别在13-30和30-50℃范围时,它们的lnKSL分别随绝对温度的倒数线性变化;而在PEG-400和修饰的PEG-400疏水色谱介质上,当温度分别在13-40和13-30℃范围时,它们的lnKSL分别随绝对温度的倒数线性减小,但当温度分别高于40℃和30℃时,它们则随绝对温度的倒数剧烈减小。通过研究不同温度范围的焓变、熵变、自由能变和α-淀粉酶构象变化之间的关系,发现在RP-C18反相和Zn2+螯合的Sepharose fast-flow亲和介质上在30- 50 ℃温度范围内,在WCX-1阳离子交换介质上在13-30 ℃温度范围内,α-淀粉酶的吸附过程由焓变和熵变共同所支配,而在Zn2+螯合的Sepharose fast-flow亲和介质上在13- 30 ℃温度范围内,在WCX-1阳离子交换介质上在30-50 ℃温度范围和在PEG-400 和修饰的PEG-400疏水色谱介质上在13-65 ℃温度范围时,α-淀粉酶的吸附过程仅仅由熵变所控制。最后,通过α-淀粉酶在这些色谱体系中的补偿温度进一步发现,它们的焓变仅仅只能通过它们构象变化所引起的熵变所补偿。     

A Simple Frontal Analysis Equation to Determine the Adsorption Parameters of Solute Molecules on Different Adsorbents

A simple frontal analysis equation to determine the adsorption parameters of solute molecules on different adsorbents was presented. It gives the relationship between the average breakthrough time and the feed solute concentration, and by using its linear form, two important parameters, the thermodynamic equilibrium constant KSL for solute adsorption on the surface of adsorbent and the number nt of total adsorption sites distributed on the surface of adsorbent, can be simultaneously determined. The frontal analyses for some aromatic hydrocarbons on RP-C18 reversed-phase medium, and some protein molecules on RP-C18 reversed-phase, WCX-1 cation-exchange, PEG-400 hydrophobic and Chelating Sepharose Fast-flow separately chelated with Zn^2＋ or Cu^2＋ media, were separately carried out to test this equation and their adsorption parameters KSL and nt were separately obtained. The results show that all these frontal analysis data can be well described by this frontal analysis equation. For all of these frontal analysis systems, their parameters nt can separately approximately keep constant and they are independent of solute molecules used, while their parameters KSL are dependent upon both of the media packed in frontal analysis column and the solute molecules used.     

Selective α-Bromination of β-Keto Esters in Reusable PEG-400 under Mild and Catalyst-free Conditions

An efficient bromination protocol for the synthesis of α-bromo-β-keto esters has been developed. In PEG-400 （poly（ethylene glycol-400））, a variety of β-keto esters were treated with NBS （N-bromosuccinimide） at room temperature to selectively afford the corresponding α-monobromination products in excellent yields. It is noteworthy that the reaction was conducted under mild, environmentally benign and catalyst-free conditions.     

β‐Hairpins Generated from Hybrid Peptide Sequences Containing both α‐ and β‐Amino Acids

The incorporation of the β‐amino acid residues into specific positions in the strands and β‐turn segments of peptide hairpins is being systematically explored. The presence of an additional torsion variable about the C(α) C(β) bond (θ) enhances the conformational repertoire in β‐residues. The conformational analysis of three designed peptide hairpins composed of α/β‐hybrid segments is described: Boc‐Leu‐Val‐Val‐^DPro‐β Phe ‐Leu‐Val‐Val‐OMe ( 1 ), Boc‐Leu‐Val‐β Val ‐^DPro‐Gly‐β Leu ‐Val‐Val‐OMe ( 2 ), and Boc‐Leu‐Val‐β Phe ‐Val‐^DPro‐Gly‐Leu‐β Phe ‐Val‐Val‐OMe ( 3 ). 500‐MHz ¹H‐NMR Analysis supports a preponderance of β‐hairpin conformation in solution for all three peptides, with critical cross‐strand NOEs providing evidence for the proposed structures. The crystal structure of peptide 2 reveals a β‐hairpin conformation with two β‐residues occupying facing, non‐H‐bonded positions in antiparallel β‐strands. Notably, βVal(3) adopts a gauche conformation about the C(α) C(β) bond (θ=+65°) without disturbing cross‐strand H‐bonding. The crystal structure of 2 , together with previously published crystal structures of peptides 3 and Boc‐β Phe ‐β Phe ‐^DPro‐Gly‐β Phe ‐β Phe ‐OMe, provide an opportunity to visualize the packing of peptide sheets with local ‘polar segments' formed as a consequence of reversal peptide‐bond orientation. The available structural evidence for hairpins suggests that β‐residues can be accommodated into nucleating turn segments and into both the H‐bonding and non‐H‐bonding positions on the strands.     

β‐Turn Analogues in Model αβ‐Hybrid Peptides: Structural Characterization of Peptides Containing β2,2Ac6c and β3,3Ac6c Residues

The effect of gem‐dialkyl substituents on the backbone conformations of β‐amino acid residues in peptides has been investigated by using four model peptides: Boc‐Xxx‐β^2,2Ac₆c(1‐aminomethylcyclohexanecarboxylic acid)‐NHMe (Xxx=Leu ( 1 ), Phe ( 2 ); Boc=tert‐butyloxycarbonyl) and Boc‐Xxx‐β^3,3Ac₆c(1‐aminocyclohexaneacetic acid)‐NHMe (Xxx=Leu ( 3 ), Phe ( 4 )). Tetrasubstituted carbon atoms restrict the ranges of stereochemically allowed conformations about flanking single bonds. The crystal structure of Boc‐Leu‐β^2,2Ac₆c‐NHMe ( 1 ) established a C₁₁ hydrogen‐bonded turn in the αβ‐hybrid sequence. The observed torsion angles (α(?≈?60°, ψ≈?30°), β(?≈?90°, θ≈60°, ψ≈?90°)) corresponded to a C₁₁ helical turn, which was a backbone‐expanded analogue of the type III β turn in αα sequences. The crystal structure of the peptide Boc‐Phe‐β^3,3Ac₆c‐NHMe ( 4 ) established a C₁₁ hydrogen‐bonded turn with distinctly different backbone torsion angles (α(?≈?60°, ψ≈120°), β(?≈60°, θ≈60°, ψ≈?60°)), which corresponded to a backbone‐expanded analogue of the type II β turn observed in αα sequences. In peptide 4 , the two molecules in the asymmetric unit adopted backbone torsion angles of opposite signs. In one of the molecules, the Phe residue adopted an unfavorable backbone conformation, with the energetic penalty being offset by a favorable aromatic interaction between proximal molecules in the crystal. NMR spectroscopy studies provided evidence for the maintenance of folded structures in solution in these αβ‐hybrid sequences.     

An analytical method for measuring α‐amylase activity in starch‐containing foods

The quality of starch‐containing foods may be significantly impaired by contamination with very small amounts of α‐amylase, which can enzymatically hydrolyze the starch and cause viscosity loss. Thus, for quality control, it is necessary to have an analytical method that can measure low amylase activity. We developed a sensitive analytical method for measuring the activity of α‐amylase (from Bacillus subtilis) in starch‐containing foods. The method consists of six steps: (1) crude extraction of α‐amylase by centrifugation and filtration; (2) α‐amylase purification by desalting and anion‐exchange chromatography; (3) reaction of the purified amylase with boron‐dipyrromethene (BODIPY)‐labeled substrate, which releases a fluorescent fragment upon digestion of the substrate, thus avoiding interference from starch derivatives in the sample; (4) stopping the reaction with acetonitrile; (5) reversed‐phase solid‐phase extraction of the fluorescent substrate to remove contaminating dye and impurities; and (6) separation and measurement of BODIPY fluorescence by HPLC. The proposed method could quantify α‐amylase activities as low as 10 mU/mL, which is enough to reduce the viscosity of starch‐containing foods. Copyright © 2012 John Wiley & Sons, Ltd.     

Anionic polymerization of 2,7‐di‐t‐butyldibenzofulvene: Synthesis,structure, and photophysical properties of the oligomers with a π‐stacked conformation

2,7‐Di‐t‐butyldibenzofulvene (tBu₂DBF), a bulky dibenzofulvene derivative, was polymerized using n‐butyllithium as initiator in tetrahydrofuran at ?78 °C and in toluene at 0 °C. tBu₂DBF afforded mainly oligomers up to trimer even at [monomer]₀/[initiator]₀ = 20 ([monomer]₀ = 0.2 M) at ?78 °C and 0 °C, indicating that this monomer is much less reactive than dibenzofulvene (DBF), its parent compound. The reaction at the same [monomer]₀/[initiator]₀ ratio at an elevated [monomer]₀ gave a small amount of insoluble polymer. The oligomers indicated a hypochromic effect in the absorption spectra and only monomer emission in the fluorescent spectra. The conformation of the trimer and the dimer was examined by means of NOESY NMR spectra and semiempirical calculations. In the trimer conformation, the fluorene moieties of the central and the initiation‐side monomeric units were found to be closely stacked on top of each other, while the termination‐side monomeric unit appeared to be in a faster conformational dynamics compared with the other monomeric units. Although the dimer seemed to have a relatively flexible conformation, a π‐stacked structure appeared to be involved in the conformational dynamics to show hypochromicity. The results of this study suggest that the reported intramolecular excited dimer (excimer) formation of the poly‐ and oligo(DBF)s [J Am Chem Soc 2003, 125, 15474] is based on a slight, local conformational change upon photo absorption, leading to a closer π‐stacked alignment of two neighboring fluorene units than that in the ground state. Such a local conformational transition may be difficult for the tBu₂DBF trimer because of steric repulsion of the t‐butyl groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 561–572, 2006     

The First Fully Planar C5‐Conformation of Homooligopeptides Prepared from a Chiral α‐Ethylated α,α‐Disubstituted Amino Acid: (S)‐Butylethylglycine (=(2S)‐2‐Amino‐2‐ethylhexanoic Acid)

An optically active α‐ethylated α,α‐disubstituted amino acid, (S)‐butylethylglycine (=(2S)‐2‐amino‐2‐ethylhexanoic acid; (S)‐Beg; (S)‐ 2 ), was prepared starting from butyl ethyl ketone ( 1 ) by the Strecker method and enzymatic kinetic resolution of the racemic amino acid. Homooligopeptides containing (S)‐Beg (up to hexapeptide) were synthesized by conventional solution methods. An ethyl ester was used for the protection at the C‐terminus, and a trifluoroacetyl group was used for the N‐terminus of the peptides. The structures of tri‐ and tetrapeptides 5 and 6 in the solid state were solved by X‐ray crystallographic analysis, and were shown to have a bent planar C₅‐conformation (tripeptide) and a fully planar C₅‐conformation (tetrapeptide) (see Figs. 1 and 2, resp.). The IR and ¹H‐NMR spectra of hexapeptide 8 revealed that the dominant conformation in CDCl₃ solution was also a fully planar C₅‐conformation. These results show for the first time that the preferred conformation of homopeptides containing a chiral α‐ethylated α,α‐disubstituted amino acid is a planar C₅‐conformation.     

Influence of fluorine substitution on the molecular conformation of 3′‐deoxy‐3′‐fluoro‐5‐methyluridine

Fluorine substitutions on the furanose ring of nucleosides are known to strongly influence the conformational properties of oligonucleotides. In order to assess the effect of fluorine on the conformation of 3′‐deoxy‐3′‐fluoro‐5‐methyluridine (^RT^F), C₁₀H₁₃FN₂O₅, we studied its stereochemistry in the crystalline state using X‐ray crystallography. The compound crystallizes in the chiral orthorhombic space group P2₁2₁2₁ and contains two symmetry‐independent molecules (A and B) in the asymmetric unit. The furanose ring in molecules A and B adopts conformations between envelope (²E, 2′‐endo, P = 162°) and twisted (²T₃, 2′‐endo and 3′exo, P = 180°), with pseudorotation phase angles (P) of 164.3 and 170.2°, respectively. The maximum puckering amplitudes, ν_max, for molecules A and B are 38.8 and 36.1°, respectively. In contrast, for 5‐methyluridine (^RT^OH), the value of P is 21.2°, which is between the ³E (3′‐endo, P = 18.0°) and ³T₄ (3′‐endo and 4′‐exo, P = 36°) conformations. The value of ν_max for ^RT^OH is 41.29°. Molecules A and B of ^RT^F generate respective helical assemblies across the crystallographic 2₁‐screw axis through classical N—H…O aand O—H…O hydrogen bonds supplemented by C—H…O contacts. Adjacent parallel helices of both molecules are linked to each other via O—H…O and O…π interactions.     

Theoretical Prediction of Substituent Effects on the Intrinsic Folding Properties of β‐Peptides

A systematic conformational analysis on blocked β‐amino acids as constituents of β‐peptides by ab initio MO theory reveals that the conformer pool of β‐peptide monomers is essentially determined by the conformation of simple submonomer fragments. The influence of single and multiple substitutions at the C(α) and C(β) backbone atoms on the intrinsic folding properties of the monomers was estimated both in the single‐molecule approximation and in a polar solvent continuum, applying a quantum‐chemical SCRF model. Substitution at C(β) has a higher impact on the β‐amino acid conformation than a substitution at C(α). It can be shown that the conformations of important periodic secondary structures in β‐peptides belong to the conformer pool of the monomers, even for those secondary‐structure elements where H‐bond formation appears only in longer sequences. Rules for design of special secondary‐structure types by selection of an actual substituent pattern in the β‐amino acid constituents have been derived within the monomer approach.     

Validation of the GROMOS 54A7 Force Field Regarding Mixed α/β‐Peptide Molecules

A molecular‐dynamics (MD) simulation study of two heptapeptides containing α‐ and β‐amino acid residues is presented. According to NMR experiments, the two peptides differ in dominant fold when solvated in MeOH: peptide 3 adopts predominantly β‐hairpin‐like conformations, while peptide 8 adopts a 14/15‐helical fold. The MD simulations largely reproduce the experimental data. Application of NOE atom? atom distance restraining improves the agreement with experimental data, but reduces the conformational sampling. Peptide 3 shows a variety of conformations, while still agreeing with the NOE and ³J‐coupling data, whereas the conformational ensemble of peptide 8 is dominated by one helical conformation. The results confirm the suitability of the GROMOS 54A7 force field for simulation or structure refinement of mixed α/β‐peptides in MeOH.     

Supramolecular micellization and pH‐inducible gelation of a hydrophilic block copolymer by block‐specific threading of α‐cyclodextrin

A poly(ethylene glycol)‐b‐poly(L ‐lysine) diblock copolymer (PEG‐b‐PLL) was synthesized. Micellization of this hydrophilic copolymer due to the block‐specific threading of α‐cyclodextrin (α‐CD) molecules onto the polyethylene glycol (PEG) block yielded supramolecular‐structured nanoparticles, which undergoes pH‐inducible gelation in aqueous media. The pH‐inducible gelation of supramolecular micelle in water appeared to be completely reversible upon pH changes. The synergetic effect of selective complexation between PEG block and α‐CD and the pH‐inducible hydrophobic interaction between PLL blocks at pH 10 was believed to be the driving force for the formation of the supramolecular hydrogel. ¹H NMR and wide angle X‐ray diffraction (WAXD) were employed to confirm the inclusion complexation between α‐CD and PEG block. Meanwhile, the morphology of the micellized nanoparticles was investigated by transmission electron microscopy (TEM). The thermal stability of inclusion complexes (ICs) was investigated and the rheologic experiment was conducted to reveal the micelle‐gel transition. Such pH‐induced reversible micelle‐gel transition of the supramolecular aggregates may find applications in several fields, for example as advanced biomedical material possessing stimulus‐responsiveness. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 782–790, 2008     

2‐[(E)‐(4‐Hydroxy‐3‐methoxybenzylidene)amino]‐N‐(2‐methylphenyl)‐4,5,6,7‐tetrahydro‐1‐benzothiophene‐3‐carboxamide

The title compound, C₂₄H₂₄N₂O₃S, exhibits antifungal and antibacterial properties. The compound crystallizes with two molecules in the asymmetric unit, with one molecule exhibiting `orientational disorder' in the crystal structure with respect to the cyclohexene ring. The o‐toluidine groups in both molecules are noncoplanar with the respective cyclohexene‐fused thiophene ring. In both molecules, there is an intramolecular N—H...N hydrogen bond forming a pseudo‐six‐membered ring which locks the molecular conformation and eliminates conformational flexibility. The crystal structure is stabilized by O—H...O hydrogen bonds; both molecules in the asymmetric unit form independent chains, each such chain consisting of alternating `ordered' and `disordered' molecules in the crystal lattice.     

Two polymorphs of N1,N4‐bis(5‐hydroxypenta‐1,3‐diynyl)‐N1,N4‐diphenylbenzene‐1,4‐diamine

The title compound, C₂₈H₂₀N₂O₂, forms two conformational polymorphs, (I) and (II), where the molecular structures are similar except for the orientation of the two hydroxy groups. In (I), which was obtained by slow evaporation from chloroform, the two hydroxy groups have an anti conformation. The molecules form a sheet structure within the ac plane, where the hydroxy groups form zigzag hydrogen bonds. In (II), which was obtained by slow evaporation from acetonitrile, the two hydroxy groups have a syn conformation. The molecules form a double‐sheet structure within the ab plane, where the hydroxy groups form 4‐helix hydrogen bonds.     

Gelation Rate Modulation of an α‐Cyclodextrin and Poly(ethylene glycol)‐Grafted Hyaluronic Acid Solution System by Inclusion Complexation of a Microphase‐Separated Structure

Summary: The gelation rate of a poly(ethylene glycol)‐grafted hyaluronic acid (PEG‐graft‐HA) solution with adding α‐CD was investigated in term of the microphase separation between the grafted PEG and HA. The gelation rate of PEG‐graft‐HA exhibiting the microphase‐separated structure was two times higher than that of PEG‐graft‐HA showing a homogeneous miscible state.

The formation of microphases by PEG‐graft‐HA contributes to its rapid gelation upon the addition of α‐CDs.     

The epimeric 9‐oxobicyclo[3.3.1]nonane‐3‐carboxylic acids: hydrogen‐bonding patterns of the endo acid and the lactol of the exo acid

The two δ‐keto carboxylic acids of the title, both C₁₀H₁₄O₃, are epimeric at the site of carboxyl attachment. The endo (3α) epimer, (I), has its keto‐acid ring in a boat conformation, with the tilt of the carboxyl group creating conformational chirality. The mol­ecules form hydrogen bonds by centrosymmetric pairing of carboxyl groups across the corners of the chosen cell [O⃛O = 2.671 (2) Å and O—H⃛O = 179 (2)°]. Two close intermolecular C—H⃛O contacts exist for the ketone. The exo (3β) epimer exists in the closed ring–chain tautomeric form as the lactol, 8‐hydroxy‐9‐oxatri­cyclo­[5.3.1.0^3,8]­undecan‐10‐one, (II). The mol­ecules have conformational chirality, and the hydrogen‐bonding scheme involves intermolecular hydroxyl‐to‐carbonyl chains of mol­ecules screw‐related in b [O⃛O = 2.741 (2) Å and O—H⃛O = 177 (2)°].     

Construction of temperature responsive hybrid crosslinked self‐assemblies based on PEG‐b‐P(MMA‐co‐MPMA)‐b‐PNIPAAm triblock copolymer: ATRP synthesis and thermoinduced association behavior

A novel amphiphilic thermosensitive poly(ethylene glycol)₄₅‐b‐poly(methyl methacrylate₄₆‐co‐3‐(trimethoxysilyl)propyl methacrylate)₂‐b‐poly(N‐isopropylacrylamide)₄₂₉ (PEG₄₅‐b‐P(MMA₄₆‐co‐MPMA₂)‐b‐PNIPAAm₄₂₉) triblock copolymer was synthesized via consecutive atom transfer radical polymerization techniques. The thermoinduced association behavior of the resulting triblock copolymers in aqueous medium was further investigated in detail by ¹H NMR, transmission electron microscopy, and dynamic light scattering. The results showed that at the temperature (25 °C) below the LCST, PEG₄₅‐b‐P(MMA₄₆‐co‐MPMA₂)‐b‐PNIPAAm₄₂₉ triblock copolymers self‐assembled into the core crosslinked micelles with the hydrophobic P(MMA‐co‐MPMA) block constructing a dense core, protected by the mixed soluble PEG and PNIPAAm chains acting as a hydrophilic shell simultaneously. With an increase in temperature, the resulting core‐shell micelles converted into a new type of micelles with the hydrophilic PEG chains stretching out from the hydrophobic core through the collapsed PNIPAAm shell. On the other hand, at the temperature (40 °C) above the LCST, such triblock copolymers formed the crosslinked vesicles with the hydrophobic PNIPAAm and P(MMA‐co‐MPMA) blocks constructing a membrane core and the soluble PEG chains building the hydrophilic lumen and the shell. On further decreasing the temperature, the resulting vesicles underwent transformation from the shrunken to the expanded status, leading to the formation of swollen vesicles with enlarged size. This study is believed to present the first formation of two types of hybrid crosslinked self‐assemblies by thermoinduced regulation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A Novel Synthesis of 2‐Ferrocenoyl‐Substituted Iodobenzofurans

In the present investigation, the first construction of a series of structurally new 2‐ferrocenoyl‐substituted iodobenzofurans hybrids has been achieved through a simple and mild two‐step procedure, involving the iodination of salicylaldehydes using N‐iodosuccinimide reagent in eco‐friendly PEG‐400 medium at room temperature followed by one‐pot Rap–Stoermer reaction with 1‐chloroacetylferrocene in refluxing MeCN with the presence of K₂CO₃ as base and PEG‐400 as the activated additive. These newly synthesized compounds belong to a new class of ferrocene‐benzofuran hybrids and could be good candidates for the development of compounds for use in medicinal chemistry.     

Conformation of Peptides Containing a Chiral α‐Ethylated α,α‐Disubstituted α‐Amino Acid: (S)‐α‐Ethylleucine (=(2S)‐2‐Amino‐2‐ethyl‐4‐methylpentanoic Acid) within Sequences of Dimethylglycine and Diethylglycine Residues

An optically active (S)‐α‐ethylleucine ((S)‐αEtLeu) as a chiral α‐ethylated α,α‐disubstituted α‐amino acid was synthesized by means of a chiral acetal auxiliary of (R,R)‐cyclohexane‐1,2‐diol. The chiral α‐ethylated α,α‐disubstituted amino acid (S)‐αEtLeu was introduced into the peptides constructed from 2‐aminoisobutyric acid (=dimethylglycine, Aib), and also into the peptide prepared from diethylglycine (Deg). The X‐ray crystallographic analysis revealed that both right‐handed (P) and left‐handed (M) 3₁₀‐helical structures exist in the solid state of CF₃CO‐(Aib)₂‐[(S)‐αEtLeu]‐(Aib)₂‐OEt ( 14 ) and CF₃CO‐[(S)‐αEtLeu]‐(Deg)₄‐OEt ( 18 ), respectively. The IR, CD, and ¹H‐NMR spectra indicated that the dominant conformation of pentapeptides 14 and CF₃CO‐[(S)‐αEtLeu]‐(Aib)₄‐OEt ( 16 ) in solution is a 3₁₀‐helical structure, and that of 18 in solution is a planar C₅ conformation. The conformation of peptides was also studied by molecular‐mechanics calculations.     

胸腺素α1类似物的定点PEG修饰及其免疫活性评价

PEG修饰是改善蛋白质及肽类药物药代动力学特性的有效途径。然而与蛋白质相比，肽类化合物的分子较小，PEG的分子体积较大，其长链很可能会遮蔽肽的活性位点。因此，肽类化合物PEG修饰的位置和数量对于保持肽的生物活性至关重要。为阐明PEG修饰的位置与肽生物活性之间的关系，对肽类药物日达仙（胸腺素α1，Tα1）进行了定点修饰。Tα1具有α-螺旋、β-转角和无规卷曲的结构区域。分别在这些区域选择不同的位点进行PEG修饰。PEG的定点修饰是通过引入Cys，利用其-SH与mPEG-MAL的特异性反应而实现的。Con A刺激下的脾细胞产生IFN-γ试验的初步结果表明，PEG修饰对活性的影响与修饰的位置有一定的关系，大多数情况下，PEG修饰能保持Tα1的免疫活性。PEG修饰的位点对于保持肽的生物活性是很重要的。