Summary 1The variation of floral sex allocation with flower position within inflorescences was investigated in the spring ephemeral, Corydalis ambigua . Investment in female function ( pistil), attraction (corolla) and nectar production decreased from bottom to top flowers, whereas male investment (stamen) did not differ. 2 This self-incompatible species appears to set seeds as a result of visitation by nectar robbing bumblebee queens. The tendency of bees to visit lower flowers first and then move upwards within an inflorescence should result in directional pollen flow from bottom to top flowers. 3 Naturally pollinated upper flowers set fewer seeds than intermediate and lower flowers due to pollen limitation. The lack of differences in seed set and seed mass per pod following artificial outcrossing indicated that resource limitation did not explain the variation in seed production of flowers in different positions. Pollen viability also did not differ significantly between flower positions. 4 A model of pollination was developed that incorporated the visitation pattern of bumblebees and observed variations in nectar distribution between flower positions. This predicted that receipt of outcross pollen would decrease from bottom to top flowers, but that pollen export to other plants would not differ between flower positions provided that the pollen exchange rate of pollinators was either small or positively correlated with nectar content of each flower position. The observed pattern of floral sex allocation would then be parallel to relative success of pollen export and import between flower positions within inflorescences.

(1) A brief method for the characterization of carboxyl-terminal amino acids in peptides and proteins was investigated. (2) Several new amino acid hydrazides were synthesized. (3) Soveral di- and tri-peptides were hydrazinolyzed and identified their carboxylterminal amino acid. (4) The method was applied to beef insulin and tyrocidin for the demonstration of its applicability.

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Introduction. Taka-amylase A (TAA) [EC 3.2.1.1 a-1,4-glucan 4-glucanohydrolase, Aspergillus oryzae] which was crystallized first by Akabori et al. in 19511) is a glycoprotein consisting of a single polypeptide chain of 478 amino acid residues with an amino (N)terminal alanine and a carboxy (C)-terminal serine.2~'3> The partial amino acid sequences of the N-and C-terminal regions,4~ '5> the carbohydrate chain structure° 7) and X-ray crystallographic analysis8> of the enzyme have been reported. This paper describes the complete amino acid sequence of TAA. Materials and methods. Crystalline TAA prepared from Takadiastase Sankyo9> was further purified by DEAE-cellulose column chromatography.10~ The homogeneous enzyme judged by polyacrylamide gel electrophoresis was reduced and carboxymethylated.'1 The cyanogen bromide cleavage at methionine residues of the reducedcarboxymethylated TAA (RCM-TAA) was performed in 70% formic acid for 24 h at room temperature. After removal of excess reagents by repeated lyophilization, the CNBr fragments were fractionated by gel filtration on a Sephadex G-75 column, by affinity chromatography on a Concanavalin A-Sepharose column, by ion-exchange chromatography on a SP-Sephadex C-25 column or an AG50W x 2 column and by paper electrophoresis. Methionine-containing peptides were isolated from tryptic and chymotryptic digests of maleylated RCM-TAA by a combination of gel filtration on Sephadex G-75 and G-50 columns, paper electrophoresis and high performance liquid chromatography. Amino acid compositions of peptides were determined with a Hitachi 8355 automated amino acid analyzer after hydrolysis of the samples with twice-distilled HCl containing 1 (v/v) phenol in evacuated sealed tubes at 110°C for 24, 48 and 72 h. Sequence analyses of the fragments were mostly performed by automated Edman degradation using a Beckman model 890C liquidphase sequencer in the presence of Polybrenel2) or an LKB 4020 College,

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The two dissimilar composite polypeptide chains (A and B) in beta1-bungarotoxin were isolated as their reduced and carboxymethylated derivatives as reported in the preceding paper. The N-terminal sequences were determined with a sequenator up to the 39th residue for the RCM-A chain and up to the 25th residue for the RCM-B chain with repetitive yields of 90-95%. The tryptic and chymotryptic peptides from the two chains were isolated and their structures were determined by manual Edman degradation together with dansyl-Edman and carboxypeptidases A and Y. To complete the primary structures of the two chains, information on the tryptic peptides derived from the maleylated derivatives of the two chains was also used. The completed amino acid sequence of the A chain containing 120 residues (molecular weight, 13,500) is similar to that of notexin, a presynaptic neurotoxin from Australian tiger snake venom, and phospholipases A from other snake venoms. The amino acid sequence of the 60 residues in the B chain (molecular weight, 7,000) bears no resemblance to any basic polypeptides from snake venoms. The B chain probably plays a significant role by interacting with some components in presynaptic membranes of neurosmuscular junctions.