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Polymer networks have been constructed through host-guest inclusion between β-cyclodextrin (β-CD) and 1-(2-aminoethyl)amidoadmantyl (ADen) substituents on poly(acrylic acid) (PAA). The structure of the networks and the host-guest interactions between the β-CD and ADen groups were studied by rheology and 2D 1 H NOESY NMR spectroscopy. The maximum viscosity of the mixture of β-CD substituted PAA (β-CDPAA) and ADen substituted PAA (ADenPAA) occurred at a 1:1 β-CD:ADen substituent ratio which confirmed their binary inclusion. The viscosity of the mixture of the two polymers decreased upon addition of native β-CD due to its ability to compete favorably with the β-CD substituents of β-CDPAA in the inclusion of the ADen substituents of ADenPAA and the consequent disintegration of the polymer network. The rheological properties of the polymer networks were temperature sensitive. In the temperature range 10-35 °C, the storage modulus and the loss modulus obeyed a time-temperature superposition. The horizontal and vertical temperature shift factors, a T and b T , obeyed a simple Arrhenius relationship for which the activation energies were found to be 70.3 ( 0.4 and -2.2 ( 0.1 kJ mol -1 , respectively. 2D 1 H NOESY NMR studies showed the ADen substituent to be included within the native β-CD and β-CD substituent cavities.

In order to elucidate the role of the N-terminus of insulin-like growth factor 1 (IGF-1) with respect to its biological properties, we chemically synthesized analogues of IGF-1 truncated by one to five amino acid residues from the N-terminus. In a bioassay that measured the stimulation of protein synthesis in rat L6 myoblasts, the concentrations required to produce a half-maximal response were: IGF-1, 13 ng/ml; des-(1)-IGF-1, 10 ng/ml; des-(1-2)-IGF-1, 13 ng/ml; des-(1-3)-IGF-1, 1.5 ng/ml; des-(1-4)-IGF-1, 5.1 ng/ml; des-(1-5)-IGF-1, 1200 ng/ml. When tested for their abilities to compete with 125I-IGF-1 binding to L6 myoblasts at 3 degrees C, the concentrations required for 50% competition were: IGF-1, des-(1)-IGF-1 and des-(1-2)-IGF-1, 20 ng/ml; des-(1-3)-IGF-1, 14 ng/ml; des-(1-4)-IGF-1, 40 ng/ml; des-(1-5)-IGF-1, greater than 1000 ng/ml. Receptor-binding experiments at 25 degrees C, however, gave results suggesting that the myoblasts were secreting a binding protein selective for the three longest peptides. This interpretation was confirmed by binding studies with medium conditioned by the L6 myoblasts as well as binding protein purified from MDBK-cell-conditioned medium. In both cases IGF-1, des-(1)-IGF-1 and des-(1-2)-IGF-1 competed for tracer IGF-1 binding at least 60-fold better than did the three shorter peptides. The results obtained account for the increased potency of des-(1-3)-IGF-1 and des-(1-4)-IGF-1, since their activities are not attenuated by the binding protein, and the relatively lower potency of des-(1-4)-IGF-1 is a consequence of this peptide binding less well to the L6-myoblast receptor.

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Apple pomace, a by-product of juice production, is a high-fibre, high-polyphenol functional food ingredient.

A potentiometric titration study in aqueous solution (I = 0.10 mol dm-3, KCI) of the complexation of benzoic, 4-methylbenzoic and (RS)-2-phenylpropanoic acids (HA) and their conjugate bases (A-) with Bcyclodextrin, BCD, and its substituted analogue, 6A-amino-6A-deoxy-~-cyclodextrin, BCDNH, , in which a primary hydroxy group is replaced by an amino group which may be protonated to produce a singly charged species, BCDNH; , is reported. At 298.2 K the stability constants for the complexes have the values (in dm3 mol-') shown in parentheses : benzoic acid * BCD (K, HA = 590 & 60) ; benzoate PCD (K, A = 60 f 10) ; benzoic acid * BCDNH; (K,,, = 340 f 30) ; benzoate . BCDNH; ( K ~A = 120 & 20) ; benzoate . BCDNH, (K3A = 50 f 20) ; 4-methylbenzoic acid -PCD (K, HA = 1680 & 90) ; Cmethylbenzoate -BCD (K,, = 110 f 1) ; 4-methylbenzoic acid * BCDNH; ( K 2 H A = 910 f 20); 4-methylbenzoate -BCDNH; ( K 2 A = 330 & 20); and 4-methylbenzoate . PCDNH, (K3A = 100 & 20).These data indicate that for a given cyclodextrin the guest carboxylic acids form complexes of higher stability than do their conjugate base analogues, and that BCDNH; forms more stable complexes with the conjugate bases than do BCD and PCDNH,. These trends are also observed for the complexation of (RS)-2-phenylpropanoic acid and (RS)-2-phenylpropanoate where the complexes indicated are characterised by the stability constants (in dm3 mol-') shown in parentheses: (RS)-2-phenylpropanoic acid. BCD ( K , R H A = 1090 k 30, K,,,, = 1010 f 40) ; (RS)-2-phenylpropanoate * PCD (K, , , = 63 f 8, K,,, = 52 & 5) ; (RS)-2-phenylpropanoic K,,, = 110 f 10); and (RS)-2-phenylpropanoate BCDNH, (K3,, = 36 f 6, K3,A = 13 & 7). These data also show that while K1,HA and K i s H A , and K , , , and KISA are indistinguishable for (RS)-2-phenylpropanoic acid * BCD and (RS)-2-phenylpropanoate * BCD, chiral discrimination is indicated by K,,HA > K2sHA for (RS)-2-phenylpropanoic acid BCDNH;, K,,, > KZSA for (RS)-2-phenylpropanoate -PCDNH; , and K3,, > KBSA for (RS)-2phenylpropanoate -BCDNH, . The ' H NMR spectra of the methyl groups of the enantiomers of (RS)-2-phenylpropanoic acid appear as two separate doublets, indicating chiral discrimination when complexed by BCD or BCDNH; , but such chiral discrimination is not observed for (RS)-2-phenylpropanoate when complexed by PCDNH; . The implications of these observations are discussed. acid * BCDNH; (K2RHA = 580 f 20, K~,HA = 480 & 10); (RS)-2-phenylpropanoate * BCDNH;