Table 1. Oligonucleotides prepared and used in this study.

Oligomer	Sequence 5′ → 3′a	Target site (exon 4)	Tm (°C)b	ESI-MSc, calc.	ESI-MSc, found
tc1	pCTTAC′CACT*	5′ss	56.4	3281.4	3282.9
tc2	pCCTTAC′CACTC*	5′ss	69.3	3935.8	3937.0
tc3	pCCCTTAC′CACTCA	5′ss	77.4	4388.2	4389.0
tc4	pACCCTTAC′CACTCAG	5′ss	83.2	5106.7	5107.6
tc5	pACCCTTAA′CTCTCAG	5′ss	60.2	5121.7	5121.5
tc6	pACCACC′CTGTCAA-FAM	3′ss	–	5035.0	5034.8
tcNS	pCATTATTGCCCTGAAAGa	–	–	6210.2	6209.3
lna1	CTTAC′CACT	5′ss	82.6	2942.5	2941.0
lna2	CCTTAC′CACTC	5′ss	≈95	3605.3	3604.0
lna3	CCCTTAC′CACTCA	5′ss	>95	4277.9	4276.2
lna4	ACCCTTAC′CACTCAG	5′ss	>95	4976.3	4976.1
lna5	ACCCTTAA′CTCTCAG	5′ss	92.3	4977.3	4975.0
lna6	ACCACC′CTGTCAA-FAM	3′ss	–	4908.3	4907.0

^aBold italic: mismatch position; C: 5-methylcytosine; a: 2′-deoxyadenosine; (′) denotes the splice position on the pre-mRNA; (*) denotes a 3′-terminal modification by a 2,5-dimethoxytetrahydrofuran-3,4-diol unit (see Materials and Methods).

^bT_m values (2 µM duplex in 10 mM NaH₂PO₄, 150 mM NaCl, pH 7.0) were measured with the RNA complement r(ACUGAGUGGUAAGGGUA).

^cMolecular masses were recorded in the negative ion mode and are indicated as [M-H]^–.